The  NC-4  transatlantic  flight  seaplane  aloft,  as  seen  from  one  of  her  companion  flying  boats 


The  Vickers  "  Vimy  "  bomber  leaving  St.  John's  for  the  non-stop  transatlantic  flight 


.TEXTBOOK 

OF 

APPLIED 
AERONAUTIC  ENGINEERING 


HY 


HENRY  WOODHOUSE 


u  IHOR  OF  "TEXTBOOK  or  KAVAI    AEBONAI  n.  »."   "IIXTBOOK  or  MILITARY 

AERONAUTICS,"  "AIRO  BIXE  BOOK." 
MEMBER  or  TIM:  BOARD  of  UOVKRNORR  or  AKRO  nr»  or  AMERICA.  vici-l-Rrsn..  v  t 

AKRIAl     I  I  V..'   r.   Or    AMERICA,    MEMBER    OF  NATIONAL   AERIAL   COAST   FATROL  COM- 

MI-.IMS.    III.  Mil     VM..IIVI..MVX    ol    COMMITTEE  OK   AERONAl'TK  «  NATIONAL 

iv-HTITr    OF    Fill.  II-  Y.    MEMBER    OF   THE    gOCIKTY    Ot    AVTOMOTITE 

ri    «-|U»M      VM>     INDI-ITBIAI.    DEI.EOATE 
PAN-AMERICAN    FEDERATION.    ETC.,    ETC.,    ETC. 


NEW  YORK 
THE  CENTURY  CO. 

1920 


3 


Copyright,  1920,  by 
THE  CENTUBY  Co. 


Published,  January,  1920 


Textbook  of  Applied  Aeronautic  Engineering 


INTRODUCTION 


Thi-    ni-nunm-nt.-il    work    on    aeronautic    •  -n-in,  -.  mi-    i- 
,-inl    importance    .-ind    value    .-it    this    time    In  cause    it 
tells  in  a  simple  laminate,  anil  without  difficult   formulas. 
Imu    l.-iri."     •icroplancs  ..in   !»•   Imilt    for  arrial   transporta- 
.TII!.    by    i:ivini:   tin     drawings,    ili  aurains    and    photo- 
graph-   iif    existing    ami     (iroposrcl     types     of    aeroplane- 
.•iii,l    i  «.  iltli  nt  engineering  data,  will  ,-issist  engineers  in 
hiiildint:  aeroplane-  large  and  small,   for  .-irri.-il  transporta- 

•ul   other   purposes. 

While    travelliii!:   tlirouiili    South    and    Central    Am- ri.- i 

\     I    was    n-mimli-d    daily    that    South    and    Central 

rii-a     in     waiting    f»r    aerial    transportation. 

In    tin  «i    eoiintrii-s   we    have    many    ditlieult    prolili-nis   of 

traiisportati..ii    whieh    eati    lie    easily    solved    liy     aircraft. 

L'pon    the    solution    of    this,      prohlems    depends    the    cco- 

noniie  wcifa'rc  and  eiiiiim-rei.il  developmi-nt  of  these  roun- 

trie-.  »  lii  re   mountains,   forests   and   waterways  make   the 

of   building   railroads    prohihitiv- 

The  stupendous  flights  of  the  X.  ('.  I.  the  Vickers 
"Vimy  and  other  large  aeroplanes  have  aroused  hopes 
that  i.  rial  transportation  lines  will  be  established  in  the 

future. 

In  everv  o n.  of  tin  Latin  Amerieaii  countries  there  arc 
people  with  imagination  and  capital  who  would  like  to 
tak.  steps  to  establish  air  lines,  but  they  do  not  quite 
know  how  to  go  about  it.  Soon,  we  hope,  enterprising 
experts  in  the  I  'nit-d  States  will  come  to  our  assistance 
and  establish  these  lines. 

While  tin-  I'an  American  aeronautic  movement  is  youth- 
ful, having  IM-I-II  conceived  by  Mr.  Henry  WoodhoUM  in 
I'll  I.  and  -volvcd  l>y  him  and  the  other  energetic  and 
•  in-  men.  who  are  responsible  for  so  many  im- 
portant aeronautic  movements —  Messrs.  Alan  R.  Hawley. 
H.  ar  Vdmiral  Hob,  rt  K.  Peary,  John  Barrett,  and  Henry 
A.  \\  i-  Wind  it  is  advancing  in  gigantic  strides. 

ins,    of   the    broad    expanse    of    territory,   the   lack 

of    roads    into   all    sections   of   the   country,   the   excellent 

ways,  all  kinds  of  aircraft  will  be  of  great  value  to 

tin     I'nitcd    States   and    Canada,   as    well   as    to   South   and 

r.d   America. 

I  u.    years   ago    I    went    with    Mr.    Woodhouse    to    visit 

tin    (  urtiss   Aeroplane   factory   at    Buffalo.      The   pur|M>sc 

of  our  visit   was  to  prove  to  ourselves  that  an  aeroplane 

.etually   being   built   that  could  lift  a   ton.      Reports 

had    bei  n   circulated    that    such    an    aeroplane    was    being 


designed,  but  the  thing  was  not  considered  possible  or 
practical.  Mr.  Woodhouse  and  mvs.l!  had  IM-I-II  study- 
ing the  need  of  aerial  transportation  in  South  ami  <  •  n 
tral  Am.  ne.i  and  w.  rcali/.rd  that,  if  it  was  true  that 
such  an  aeroplane  was  Ix-ing  built,  there  were  prospects  for 
the  establishing  of  aerial  transportation  lines  in  South 
and  Central  America  within  a  few  years,  which  would 
solve  the  difficult  problems  of  transportation.  We  went 
to  HuH'alo  with  keen  ,  \peetation.  but  did  not  expect  to 
actually  see  a  large  aeroplane  under  construction,  be- 
cause at  the  time  even  the  highest  engineers  did  not 
admit  the  possibility  of  building  large  aeroplanes  that 
would  fly  successfully.  They  generally  held  that  a,  n. 
planes  with  two  motors  were  impractical,  because  in  the 
event  of  one  motor  stopping,  the  aeroplane,  according 
to  their  computations,  would  spin  around  and  it  would 
be  impossible  for  the  pilot  to  control  it.  They  also  held 
that  propellers  would  not  stand  the  vibrations  of  high 
horse  power  engines. 

To  our  great  satisfaction  and  wonderment  we  found 
in  the  Curtiss  factory  a  huge  seaplane  almost  completed 
which,  we  know  now.  was  a  prototype  of  the  N.  C  I. 
which  Hew  across  the  Atlantic. 

I  clearly  recall  how  very  few  people  believed  an 
when  we  reported  to  them  what  we  had  seen.  It  seemed 
impossible ! 

In  this  valuable  Textbook.  Mr.  \Voodhousc  points  out 
the  possibility  of  building  aeroplanes  to  lift  twenty  tons 
of  useful  load,  and  he  explain*  hou-  H  can  be  done! 
It  is  not  prophecy  on  his  part;  it  is  knowledge  of  the 
broadest  aspects  of  aeronautic  engineering  and  of  the 
aeronautic  art  as  a  whole,  with  the  development  of  which 
he  has  Ix-cn  closely  identified  for  the  past  ten  years. 

Furthermore.  Mr.  Womlhouse  urges  original  experi- 
ments in  the  distribution  of  the  10,000  square  feet  of 
wing  space  which  is  required  to  lift  twenty  tons  of  us, 

ful  load. 

He  presents  the  problems  to  be  solved  in  clear,  simple 
language  and  clearly  defines  the  factors  which  will  make 
for  success  in  developing  large  machines  for  aerial  trans- 
portation. Then-fore,  this  Textbook  will  be  of  great 
assistance  to  aeronautic  engineers  and  to  every  IMTSOII 
who  is  interested  in  the  development  of  aerial  trans- 
portation and  the  use  of  aeroplanes  for  general  purP 

ALBERTO  SANTOS-DI-MONT, 

Honorary  Prrtiilrnl  l'a»-.-lmrrira» 

.Irronaulir  pntrratiii*. 


r,   .; 


CONTENTS 


PAGE 

CHAPTER   I     STATI-S  OF  APPLIED  AERONAITI.    Bva 

NKKUINIi 3 

\\.ir  Developed  Speed  Kcgardlcss  of  Klying  Kfficicllt-y          3 
,t    Bomliini:  and  Antiaircraft   llrnii^ht   . \lMint   Vnl- 
lialilr    DcM-lop  Mil-lit-,    ill    AiTi>|.|.-inr    Construction     .  5 

K.ngiiiecrintr    \il\antiijrcs  in   I  Urge    M  i.  hines       ...          o 

Phwoixl  Coiistrm  -lion  Our  »t    Most    Important    l>,\.| 
incuts 

T\p.sot    II.  .*icr  Th.in    \ir   Aircraft 7 

Status  .if   Present    l>.-i>    Aeroplanes      . 

Detailed   Views  of  NC-l  Transatlantic  T\  pc  Seaplane       12 

Cellini:   tin-    Sniiif    KngiMccring    liesiilts   liy    Diffi-rrnt 

Distriliiiti.uis    of    \Vin;r     \re.i    ....  14 

Mow   Can    \Vr    DistriUitc   tli.-    KM«KI   Square    Feet   of 
Wing  Surface    ltri|iiiri-.l   to   Lift    -'»  Tons  of   L'se- 

ful    l.oadr 1  • 

\rca  Distrih-ition.  Win^s  with    \-pcct   Uatin  of  6  to  1       17 

Kclation   of  Cap   to  Chord 17 

Tandem    Planes    lti-pr.--.-nt    tin-  Solution 

I'rolilenis  of  Trussing  HIM!   Bracing 

B.xlv  C. instruct  ion 19 


II      Mi  I.TI 


AEROPLANES 


23 


The  .i-Motornl  C.-riiian    Biplane      . 

Tlir    l-Motornl    Voisin   Triplane      .......  -'•"' 

Hi,-    t   Moton-d   llaiidlcy-Pagc   Biplane      .....  -•'> 

III.-    l-Mot.ir<-il   Sikorsky    Biplane   .......  -' 

Hi,     I   M,.lor,-d  Zeppelin    Biplane        .      . 

x  -Curtiss   No    I  TnuiMitlantic-  SfiijtUne  33 

The  Capraol  Bombing  TrtpUne  Type  CA-4  .     ...  37 

Curtiss   II   li-  A    l-'lyinu   Boat      ........  41 

I     ,  I     \  ivj    I  l\ini:   Uoit      .      .      . 

il.in.ll.->  Page  Type  O-MM  Bomber  .....  +7 

Tlir    Martin  Cruisinjr   Bomljer   ........  *0 

Cl.-iiii   1..    Martin    Bomlx-r      .........  •'• 

Siiiulstitlt-lliinnrvi);   Si-a]>lnnr      ...... 

Bur^'--'  Twin-.Motcin-il  llydroai-roplani-  .....  59 

Thr  TransatlantU-  'I'vpr  VirkiTs  -  \'iiny  "     ....  60 

Uro  Twin   l-'.njrini-d   Bonilx-r   .      .      . 
Ijiwson    Aerial    Transport     . 

The   Krii-ilri.-li-.hafm  Twin-Motoml   Biplane      ...  67 
The  Cotlia   Twin-Motor.-d    Biplane  -  Type  (5O.  G5    . 

The  C.-rman  A.   K.  C  .  ({.milling  Biplane       ....  79 

Cnrtixs   M.xlrl  1H-B   Biplane    .......  "0 

The  Cnrti-s  "Oriole"   Biplane       .......  81 

C'n  \PTER   III     SiNoi.K  MOTORED  AEROPLANES     .      .  82 


The  Ai-riniiiiriiK-  Tniininp  Tractor       ...... 

The   Hellnnea   Biplane       ..........       «* 

Cnrtiss  M.Hlrl  .IN-tl)  Tra.-tor  ........       87 

The  IV  Havillan.l  t  Trai-tor  Biplane  ......       *» 

The  I).  II.  '.  I'ursiiit   Biplanr     ........       93 

The   I).-   llavillanil   No.  5      .........       94 

I'hr  T-l  MesM-np-r      ...........        96 

The  Berekman-.  Speeil  Si-out     ........ 

The  Christinas  Stnitlrss   Biplane   .......      101 

The  I,nws,m  M.  T.  -'  Traetor  Biplane       .      .      . 
Oallnudrt   K.-l.   .'   Mononl.inr  ... 

The  C.allnnilet  K.-l.  .'  "  Chiiiiimy  KlynlK.nt  "  Monoplane     1M 
The  I.e  Pere  Kijihter       ..........     1°" 

Onlnanre    Knaineerlne   Srout  —  SO  Ix-Rhftne      . 

The  ().  I.  .  C    TM..-S  B  ami  C  Single  Sealer  .      .      .      .      1O9 

The   Martin    K-III   Single   Sealer       ...... 

The   Parltanl    Aeroplane        .....  11* 


FAOE 

The  Standard   K-l   Single  Seater 117 

The  VK-7  TraininK  Biplam- ll« 

The  Three-Motored   White   Monoplane 119 

The  Standard    Mo.1,-1    I.   I  Mail  Aeroplane      .      .      .      .  1-'" 

Thomas-Morse,   T\|»      "•  l<     smv.|,-  ^-ater   Sront     .      .  1.'-' 

Thomas-Morse,   T\  p.      -   II     Sin^le-seiiter  Scout     .       .  1-'-' 

Thomas-Morse,  Type   -S-ti  Tandem   Two-seater      .      .  I-"-' 

Thomas-Morse,    T>pe      S   7     Side. I.) -Side     T«o-seater     .  I  .'.» 

The    Thomas-Morse    Type    M-B-H,    :«X)    h.p.    Ilispano 

Kncine    KiRhter     ." l-'l 

The   Kren.h   A.   ».   Biplane IM 

The    Bn-truet    Biplane 1JH 

The   Sopwith   Maehine 130 

The  Short   .Miii-hine ISO 

The    Martinsyde    Type l:JI 

Crahame-White     \.-ro   Limousine    . 1:1-' 

The  C.TIM:, ii   Gothas.  th.    Aviatiks  and   the   Ago   Bi- 
planes      l:« 

The   Nieiiport    P.    Planes 135 

The  S|>a.l  Seoul.  Type  S   VII I.!1' 

Bristol   Si-out       so   I.e l< hone 11:1 

I      S.   B.-l    British   Kighter 1** 

300  Hispiino-Siiizu   {'.  S.   Army  Tests 144 

Martinsydr  Seoul  —  IWKI   I  lispaiio-Suizii 147 

The  Knglish  S.   K.  :>  Single-Seiiter  Kighter   ....  151 

S.   K.  j—  IKO   llis]).ino-Suixa 154 

The    British    Sopwith    Planes .      .  15fi 

The   Sopwith    "Camel" 156 

British    Avro   Aeroplanes 157 

The  S.   V.   A.   Kiphtinp  Seoul 159 

The  I'oinilio   Heeonimissanee  T\  pe  Traetor   ....  161 

The  A.    K.  C'i.  Cerman    Armored   Biplane       ....  163 

The  German  Api   Kighling  Biplane 165 

The  Allmtros  Type  "I  V  "   1-Vt" I70 

The   Kokker  SinVlf  Seater   Biplane       T>  pe   O-7      .      .  186 

Tlie  Tarranl   "TalMir"  Triplane 191 

The    MallH-rstadl    l-'ighter '"-' 

The  Cerman   llansH-Brandenhiirg  Traetor   ....  195 

Details  of   Ihe    Austrian    Hansa-Brandeiihiirj:  Traetor  l'i; 

The  Wittemann-I.rwis  Commereial  Biplane   ....  198 

The  Holand  Chaser   I).   II -'IX) 

The   I..   V.  C.   Biplane  Type  C.   V 

The    Ae.-Mot.ired  Single  Seater   Aee   Biplane    .      .      .  iK)4 

The   Hannoveraner   Biplane 207 

IlallM-rstadt-Kil)    Mem-des JOB 

The  PfaU   Biplane   I).   Ill -M" 

Pfalr.   Seoul   S.*    I    I7-1WI    Mer.-edes JU 

Trails  on   Avialik   No.  G.IMJ.   I   .  214 
Dimensions  and  Kquipmrnt  of  Ihe  1918-1919  Types  of 

Cerman    Aeroplanes -'I* 

The  C.  IV   Kiimpler  Biplane 216 

The  Curtiss  Model   IH-T  Triplane  .... 

The   Sopwith   Triplane     . 

Perspective  Sketches  of  the  Cerman   Kokker  Triplane  J.'t 

The    Kokker   Triplane 

The  Aeromarine  Training  Seaplane 

The  Aeromarine  "  T-.VI  "  Three  Seater  Flying  Boat   . 

Boeing    Seaplane       Type    C-I-K ** 

The  Burgess  Speed  Scout  Seaplane 

The  Curtiss   II-  \    Hydro 23M 

Curtiss   M.Kl.-l    IIS- .'-I.    Klying  Boat 235 

Curtiss   M.nlel   MK   Klying  Boal     .      . 

The  Gallaudet   D-»   l.iirht   Bomlx-r  S-apliine 

Thomas-Morse  T\  pe   -S-.'.  Single-seater   Seaplane    .      .  241 

V,vi    M   .'   Bahy   Seaplane 

The'K.  B.   A.  Klying  Boat   ....  243 


CONTEXTS 


Au*triiin   Apo  Flyinsr  Boat 2*8 

The  Lohner  Flying  Boat 2*9 

CHAPTER  IV     AEROPLANE     AND     SEAPLANE     ENGI- 
NEERING         251 

CHAPTER   V     NAVY    DEPARTMENT   AEROPLANE    SPE- 
CIFICATIONS          263 

CHAPTER  VI     METHOD  OF  SELECTION  OF  AN  AERO- 
PLANE WING  AS  TO  AREA  AND  SECTION   .       .       .    271 

CHAPTER  VII      NOMOGHAPHIC      CHARTS      FOR      THE 

AERIAL  PROPELLER 276 

CHAPTER  VIII     METHODS  USED  IN  FINDING  FUSEL- 
AGE STRESSES  280 


PAGE 

CHAPTER   IX     THEORY  OF  FLIGHT 28 1 

CHAPTER  X     SHIPPING,  UNLOADING  AND  ASSEMBLING  29-1 

CHAPTER  XI     RIGGING 296 

CHAPTER  XII     ALIGNMENT 303 

CHAPTER   XIII      CARE  AND  INSPECTION     ....    308 
CHAPTER   XIV     MINOR   REPAIRS 310 

CHAPTER  XV     VALUE    OF    PLYWOOD    IN    AEROPLANE 

FUSELAGE  CONSTRUCTION 312 

Properties  of  Various   Woods 315 

CHAPTER  XVI     NOMENCLATURE    FOR    AERONAUTICS  316 
The  Metric  System .324 


TEXTBOOK 

OF 

APPLIED 
AERONAUTIC  ENGINEERING 


Hear  view  of  the  1903  Wright  1  lyrr  —  The  first   aeroplane   to  fly. 


CHAPTER  I 
STATUS  OF  APPLIED  AERONAUTIC  ENGINEERING 


Aeronautic  Kngineering  as  an  applied  art  is 
only  ;i  few  years  old. 

From  December  17.  1903.  when  the  Wrights 
made  their  first  flight,  to  1916,  tin-  world's  aero- 
nautic engineers  were  so  few  that  they  could  be 
counted  mi  one's  finger  tips. 

In  1  !»!•_>.  there  were  no  schools  of  aeronautic 
cn-rim-cring  and  Mr.  Henry  A.  Wise  Wood,  the 
editor  ,,f  "Flying  Maga/ine,"  and  the  writer 
urged  tlie  leading  Universities  to  establish  a 
course  ill  aeronautic  engineering.  Only  one 
University  responded.  The  others  stated  that 
the  need  for  such  a  course  was  not  sufficiently 
evident  to  justify  the  step. 

In  1917-1918  courses  in  aeronautic  engineer- 
ing were  established  at  a  mimlrcr  of  Universities, 
but  the  purpose  was  mainly  to  give  cadets  an 
elementary  course  on  the  theory  of  flight;  to 
teach  them  the  most  elementary  principles  in 
the  slim-test  time  possible. 

The  text  of  the  most  complete  course  of  its 
kind  is  reproduced  in  the  Index,  entitled 
"Theory  of  Flight." 

The  greatest  work  in  aeronautic  engineering 
in  the  United  States  was  done  at  the  U.  S. 


Army  Aeroplane  Engineering  Department  at 
Dayton  in  1918-1919  and  at  the  largest  aero- 
plane factories.  Their  work  was.  however,  lim- 
ited to  some  extent  by  the  exigencies  of  war, 
which  confined  them  to  the  analysis  and  con- 
struction of  only  the  types  of  aircraft  which 
were  being  considered  for  production. 

It  did  not,  to  any  extent,  bring  about  the 
combining  of  the  best  characteristics  of  different 
machines  of  different  countries,  as  might  have 
been  expected;  nor  did  it  bring  about  to  any 
extent,  the  adoption  of  best  engineering  prac- 
tice in  aircraft  construction.  This  was  due  to 
the  fact  that  the  problems  of  aeronautic  en- 
gineering were  too  complex  to  be  mastered 
within  a  year,  even  by  the  best  engineers,  and 
the  necessity  for  lightness  in  construction  did 
not  permit  the  adoption  of  automobile  or  naval 
engineering  practice. 

War  Developed  Speed  Regardles*  of  Flying 
Efficiency 

While  collectively  the  developments  in  aero- 
plane construction  brought  about  by  the  war 


N-C-1     F-LYING  BOAT 


P-5-L     PLYING    50AT 


SUNDSTtDT-HANNEVIG 


H-S  2-L    FLYING    5OAT 


McCaughlin 


STATUS  OF  . \1MM.IKI)  A  KHONAt  TU    K\<;i\  KKKINt; 


I  In- 


1  1  .inillrj  -I'ajti-     iMimlirr     ri|iii|i|>nl     with     I     Hull-  Itny   r    motor-..     Our    of    the    first     l-inotiirrd    planes    In    !«•    ]>r,>,lu.vcl. 

It   w.i-  luiilt   in  Great   Britain. 


represent  :i  stupendous  achiex cment.  we-  find 
tliat  as  :i  whole  tl;c  \\;ir  rcmiircmciits  resulted 
in  sacrificing  Hying  efficiency  for  high  speed 
and  fa-t  climbing.  Machines  \\cre  greatly 
overpowered  and  Mich  important  factors  for 
peace  Hying  as  slow  landing  speed  and  high 
gliding  angle  were  overshadowed  by  the  vital 
importance  of  fast  climbing  and  speed. 

Night  Bombing  and  Antiaircraft  Brought 

About  Valuable   Developments   in 

Aeroplane  Construction 

The  increasing  range  of  the  antiaircraft  guns 
jWeed  high  flying  and  was  responsible  for  the 
developing  of  high  ceiling  aeroplanes  of  light 
'construction  and  remarkable  efficiency.  The 
extension  of  night  bombing  operations  brought 
ahout  the  construction  of  larger  aeroplanes 
such  as  the  C'aproni,  Hand  ley- Page,  Vickers, 
A\  ro.  etc.1 

Tin-  same  thing  was  true  in  the  construction 
of  seaplanes.  The  need  of  Ion  if  distance  air 
cruisers  and  torpedoplanes  brought  ahout  the 
construction  of  large  seaplanes,  of  which  the 
\arious  I'nrtiss  types  constructed  in  the  I'nit-  1 
States  and  England  are  representative  ex:  m- 
pl- 

The  war  also  brought  about  the  construction 
of  seaplanes  capable  of  starting  from  and  land- 

Kvolutinn   of   the    Military     \eroplnnc   in   thr   "  Textbook 

of  Military     \.-ron  uitirs."   published    h\    tlie  ('••ntim    ('.•..    \.   Y. 

rntii>n     of     Marine     Flying,    "  TcxtlvKik    of     Naval 

\T,,n.nti,  s."  publish™)  by  the  Ontury  Co™  X.  Y.,  for  detailed 

lii-tory  of  thf  evolution  of  seaplane  construction. 


ing  on  fairly  rough  seas.  This  development  is 
of  great  importance  for  Hying  for  sport,  pleas- 
ure and  commerce. 

Engineering  Advantages  in  Large  Machines 

Large  machines  permit  refinements  in  con- 
struction, such  as  tic  use  of  hollow  struts  and 
hollow  members,  which  is  not  possible  in  small 
aeroplanes. 

This  has  made  it  possible  to  increase  the 
ratio  of  useful  load  by  over  ten  per  cent,  and 
to  get  nearer  the  goal  of  economic  aerial  trans- 
portation. 

It  is  hardly  necessary  to  point  out  that  the 
old  theories  to  the  effect  that  large  aeroplanes 
could  not  be  constructed  have  been  exploded. 
There  can  still  be  found  misinformed  people 
who  hold  that  as  the  thickness  of  the  wings  must 
i'-crease  in  proportion  to  the  span  of  the  win 
there  comes  a  point  where  the  weight  of  the 
wings  is  so  great  that  their  lifting  capacity  is 
not  sufficient  to  lift  the  machine  from  the 
ground. 

We  have  heard  such  foolish  arguments,  which 
for  the  past  fifteen  years,  and  up  to  the  Sum- 
r-er  of  11*17,  were  actually  responsible  for  de- 
laying the  construction  of  larger  aeroplanes  in 
the  I'nited  States  just  as  the  fallacious  theory 
that  if  one  of  the  motors  of  a  twin-motored  plane 
stopped  the  plane  would  spin  around,  delayed 
the  advent  of  twin  motored  planes.  They  are. 
at  present,  to  a  smaller  extent,  delaying  con- 
struction of  very  large  aeroplanes.  As  a  mat- 


•  STANDARD 'E -4 


THOMAS-MORSE   54- 1 


1 


VOUGHT  V.E.7 


5E  V 


McC&ughiin 


STATIS  OF  APPLIKl)  AKKONAITK     r.N(.INKI.HIM. 


t<T  .it'  t';ict.  through  tin-  development  <•!'  more 
efficient  aerofoils,  and  perfecting  (lit-  const  ruc- 
tinii  of  uings,  it  IN  no\\  po-.sihlc  to  (il)tain  wings 
capable  of  lifting  oxer  ten  pounds  per  square 
foot  while  xveighing  less  than  one  pound  per 
square  foot ! 

Plywood  Construction  One  of  Most   Impor- 
tant  Developments 

Plywood  construction  ha*  liecii  one-  of  the 
most  important  developments  of  the  past  two 
years. 

Plywood  permits,  for  instance,  the  making  of 
the  fuselage  of  an  aeroplane  in  one  piece,  on 
a  mold,  eliminating  the  tedious,  heavy,  cxpen- 
si\c  construction  of  former  days,  xxith  its  scores 
of  wires  and  tiirnhnckles. 


Plyuoo.l  ciiv.stniction  of  dilVi n  nt  parts  of 
aero]. lanes  \\iil  I cromc  ,',,!ier:d  as  soon  as  the 
vain  of  |  lywood  is  understood.1 

Types  of  Heavier  Than  Air  Aircraft 

The  main  txp.'s  of  lieav  ier-than-air  craft  an 

(1 )    The  aeroplane 

C.'i    The  helieopt.-r 

(8)    The  ornitlK.pt.  r. 

The  I'.  S.  Army  Technical  Department's 
definitions  of  these  types  can  l>e  found  in  the 
Index,  with  other  aeronautic  nomenclature. 

The  helicopter  and  the  ornithopter  were  con- 
ceived earlier  than  the  aeroplane.  Leonardo 
Da  Vinci  designed  an  ornithopter  or  Happing 
wing  machine  in  the  fifteenth  century.  Prac- 

»  S*e  Appendix  for  Chapter  on  I'lywoods  and  Veneers  In  Ano- 
plane  t'on-l ruction. 


The  Navy-Curtlss  NC-1,  the  prototype  of  the  Xavy-Curtlss  transntlnntir  seaplnnrs. 

\   n,.,,,lH-r  of  Interesting  engineering  features  are  incoVporat.-.!    in    the    .l.>ipn    in    this    machine.     T»,e   pilot    is   l,K-ate,l    outs 
ami    ,1^,    the  hull.     The  tail  unit  is  supported  by  outriggers,  instead  of  being  carried  on  the  rear  of  the  1  ull,  a. 

n  in  n  flying  txmt. 


HANDLEY  PAGE  O-400 


"A.C.E " 


LAW5ON    MT-2 


sT.vrrs  or  AIMM.IJ.D  AKUONAITH   ENGINEERING 


tic-ally  every  ^rcat  inventor  including  Thomas 
Kdison.  OrvilK-  Wright.  Louis  HIcriot,  IVter 
Cooper  Hewitt,  Kniil  licrlincr  has.  during  the 
J);l.st  tit'tci-ll  \cars  xiveil  serious  consideration  tti 

the  problem  of  building  a  helicopter.  And  v\c 
may  t\|)cct  oood  results  in  tin-  near  future. 

Now  that  tfo<nl  engines  arc  a\ailal.lc  it  is 
possible  tn  (mild  machines  capable  of  rising 
from  and  descending  to  tin-  ground  vertically. 

As  I  have  stated  in  tin-  "Textbook  of  Naval 
\  ronaiitics."  the  Danish  pioneer  aeronautic 
experimenter  Kllahamcr  baa  shown  me  the 
photograph  of  such  a  c-raft  in  lii^ht. 

Status  of  Present  Day  Aeroplanes 

./(7»y;/«///-.v  ha\(  reached  speeds  as  jrrent 
as  HiO  miles  an  hour,  have  carried  loads  ranjr- 
inu'  up  to  six  tons  and  have  reached  altitudes 
up  to  :JO. .•><)<)  t.et.  which  is  hi^hrr  than  the 


world's  highest  mountains,  and  nmre  than  50 
passen^,T>  |,;1V|.  I,,.,.,,  carried  m  i.iie  ill-lit.  In 
l.ict  the  accc.inplislimeiits  of  aeroplanes  have 
e\cee<|ed  t he  ex pectat  imis  e\  en  of  those  to  uhum 
the  suh.ject  of  aviation  has  lieen  a  life  study. 

In  spite  of  these  accomplishments,  those  \\\\<, 
can  see  the  future  of  aeronautics  from  a  hroad 
standpoint  reali/.e  that  in  so  far  as  the  construc- 
tion of  an  aeroplane  is  concerned,  aeronautics  is 
in  exactly  the  same  position  to-day  as  the  art 
»f  shipbuilding  would  he  if  ship  boilden  had 
(inly  reached  the  sta^c  of  building  racing  boats 
and  small  yachts! 

Analogous   to   the  racing   boat    we   have   the 

speed  aeroplane.       The  War  has  necessitated   the 

design  and  construction  of  small  inaehiiu  s. 
whose  prime  requisites  \\ere  jjreat  speed  and 
nianoL-uverahility  to  be  Used  for  combat  pur- 
poses. Several  successful  designs  were  worked 
out,  especially  on  the  other  side.  The  small 


'I'lii-    "  i-Vlixstowe    Fury,"    Uie    Porte   triplane    tl>  inir    boat.    This   monster   flying   boat,   thr   larp-st    in   cxlstrncr.  Is   •    Hriti.-h 
mi-    with    Hritish   rnfri'nrs.     It    is   fitted   with    five    Hnlls-Hoyrr   "  Knfrlc-s "   rnfrinrs   arrnnfml    In    tandem   wt*   and    ant   sinflc 
lii-r."     l'r<i|M-llcrs    in    tin-    tnndi-in    sets    are    four-hladed.    and   the   others   two-bladed.     Thr    tutnl    span   of   the    wings    It    IJS 
•M;  the  len(rth  <if  the  fuselafre,  60  ft.;  the  height   from  keel  to  ring  post,  27  ft  6  In.;  and  the  total  weight  i3,4OO  II. v 


sT.vrrs  OF  AIMM.IKD  AKKONAITU 


11 


Tin-    Tu  in  nintiirril    l-'iirniiiii    l>i|>l.iii< 


service  Ix-tMri-n   Paris  and  I-onclmi 
fnrtahle  <-al)in. 


•il  oom- 


wing  area  and  high  landing  speed  of  these  planes 
make  them  suitable-  only  for  \cry  expert  han- 
dling, and  for  enjoying  all  the  thrills  and  stunts 
of  expert  flying  for  sport's  sake. 

\\  •  arc  | list  beginning  to  liuild  low  priced 
aeroplanes  which  will  represent  in  aeronautics 
the  equivalent  of  the  motor  boat.  There  are 
already  small  aeroplanes  with  a  wing  spread  of 
IS  to  20  feet,  capable  of  going  at  a  speed  of  60 
to  HO  miles  per  hour,  traveling  about  '20  miles 
to  the  gallon  of  gasoline.  These  small  planes 
represent  in  aeronautics  what  the  motor  boat 
represents  in  the  marine  field  or  what  the  Ford 
and  Dodge  cars  represent  in  automobiles  and 
will  be  powerful  factors  in  popularizing  avia- 
tion. 

Hut  as  regards  large  aeroplanes.  \\e  have  only 
in  to  build  the  equivalent  of  small  yachts— 
and  to  go  beyond  this  brings  up  a  large  number 
of  problems. 

The  Navy-Curtiss  Flying  Boats  have  a  wing 
spread  of  J-jf,  feet;  the  chord  and  gap  of  the 
planes  are  !'_'  feet.  The  machine  is  driven  by 
four  Liberty  engines  of  400  h.p.  each.  A  speed 
of  over  80  miles  has  been  made,  and  in  ten 
minutes  the  machine  has  ascended  to  a  height 


of  2000  feet.  Fully  loaded  this  mac  bine  weighs 
28.000  pounds.  It  can  carry  a  useful  load 
amounting  to  more  than  six  tons.  A  more 
comprehensive  idea  of  its  carrying  capacity  may 
be  had  from  the  fact  that,  on  one  trip  .)()  people 
have  been  carried. 

While  there  are  several  planes  under  con- 
struction at  the  date  of  writing  which  have  a 
wing  span  of  up  to  100  feet,  the  \C  type  sea- 
plane and  the  Ilandley-Pauc  aeroplane  may  lie 
said  to  approach  the  limit  in  biplane  construc- 
tion. It  is  apparent  that  to  double  the  si/e  of 
the  XT  it  would  be  necessary  to  find  a  new  way 
of  distributing  the  surfaces  to  lift  such  a  large 
flying  boat. 

The  four-motored  Ilandley-Page  air  cruiser, 
which  can  carry  4'»  |  is  and  which  nas 

given  some  fine  demonstrations,  is  about  l.'iO 
feet  in  span.  It  is  apparent  also  that  this  type 
of  plane  could  not  very  well  he  double:!  in  si/e 
without  devising  a  different  method  of  distrib- 
uting the  amount  of  surface  requind  to  lift  a 
machine  of  such  proportions. 

Caproni  has  built  a  5000  hor-e  powered  tri- 
plane  and  is  now  working  on  larger  planes. 
He  has  gone  further  in  experiments  with  tri- 


Detailed  Views  of  NC-4  Transatlantic  Type  Seaplane 


1  —  Forward  part  of  hull.     The  ladder  leads  to  pilots'  cockpits. 

3 — The  commander's  cockpit  at  the  extreme  front  of  the  hull. 

5 — "Wing  tip  float  under  the  lower  left  main  plane. 

7  —  The  hiplane  tail  group.     There  are  two  fins  and  three  rudders. 


2  —  One  of  the  power  units,  showing  streamline  engine  nacelle. 

4  —  The  pilots'   compartments  showing  special  compass   installation. 

6  —  Pilots'    compartments   as    seen    from   the    front,    showing   windshields. 

8  —  Side  view  of  front  of  hull,  showing  placement  of  the  navigator. 


sT.vrrs  or  .MMM.IF.D  AF.KOX.UTU   KN^INKKKIM; 


fummmiinii 


Ilir    \I.-irt.ii    "Mini-    Mini"    ,,,,,1    tl,,-    \larlin    "  I ..,-],.  "    \niM    |,N    ,  ,,       M. ,,.,;„_   ,|,,.   ,„,,,. ()     \,m.ri,  an    ,,,-n,HMiili.'   <-n 

ftaeer.       II.,    "  Kin,-    Mini"  has   wi,,i..s  ,,,,h     Is    ,,.,  ,    „  ,,|,.   ;,,,,|  ,,nh    u,,.,,,,    ..,,  ,,,s_   wi((|   „„.  m(i||ir   ^.^   ^   |if    (||  h  ^       |(    wi||    (   ^ 
,.n    nu    ,  Mimtry    r,,.,,l    ,n,l   p,  ,,|,,,,il    .'n  mil.-s  ,,„  „   L..,||,,,,  ,,f  ^.M.li,,.-.      II,,.    Martin   "  l-:,,|rlr  "  is  <-<|iii|,|»-,l    uilli   tv»,,    IIKI  kp     I  . 

''"•-   i""1    is    r;lt"1    '"  '•;'rr>     '   l""-  "(   "--f"'    l";"1    •"'•'    ("  I»W  .,  rmisinp  r;i.lin>  ,,f  OTCt   .'"'Mi  mil,-,.      M,,tl,  i,,arl,in.  „„„,'- 

bet  of  renwrkaMe  n--«    engineering   f.-,(nr,-s  iii<-|inlinK  tin-   K-l.ar  ,-,-llul,-  truss,  tlie  retractable  c-hawiis,  ,-tc.     Tli,-  \arf,  r  m...-liiin-  has 

i  drive  truumiMion  t,,  UK-  |ir,i|>,-ll,-rs. 


plain--,  tlian  ninst  ul'  tl.c  o!ln-r  (lesion, -rs  and  lie 
f ln-rd'uiv  lias  »  :  antarc  s  i;i  that  direction, 

lint  in  plaiinintr  his  larger  |  l.iin-s  !:<•  als«.  finds 
it  necessary  to  ado;>t  diilVn-nt  |  rincipK-s  in  ciis- 
pMsin-r  of  the  enonni>"s  an  u  m  ,-i  ssary  to  oh- 
tain  the  desired  lii't  he  will  ha\e  tandem  tri- 
planes. 

In  order  to  hrin^  the  aeroplane  up  to  tin- 
standards  set  I iv  iiiarini-  einistruetors.  we  must 
de\elop  a  earjro  earryin^  tyj-e  of  plane.  It  is 


(Mivions  that  the  eoiiiinereial  value  of  this  type 
of  niaehine  is  enonnoiis.  Although  we  do  not 
hope,  at  least  for  the  pre-ent.  to  en-ate  machines 
eapahle  of  carrying  as  iniic-h  load  as  an  ocean 
goin^r  steamer,  we  do  require  a  (ilane  that  will 
carry  a  sufficiently  heavy  load,  which,  taken  to- 
gether with  the  \ast  saving  in  time,  will  make 
the  final  tonnage  transported  close  enough  for 
coiiiparisiui. 


; 


The  Ctlt-nn  I..   Martin  twin  inotornl  hiplnnr,  r<juipprd  with  two  Liberty  ni,,t,>rs. 


Getting  the  same  Engineering  Results  by  Different  Distributions  of  Wing  Area 


Bristol  Triplane,  Type  Bracinar  with  4  I'unia   Engines. 


' 


The   Pemberton-Billing  quadruplane.     Designed   by   the    English  aeronautic  enthusiast.     The  height  of  a  machine  of  this  type  be- 
gins to  be  a  serious  problem,  both  in  landing  and  in  housing  it. 


Experimental  Tandem   Biplane  of  (  olli.-x  Jeans.m.     View  of  machine   taking   off.     Wing   area,    US    sq.    meters      Span     -X    meters 
It  is  equipped  with  i  motors  of  300  h.p.  each.    Weight  of  machine,  3700  kilos. 


14 


STATt'S  OF  APPI.IKI)  AKKON.U  TIC    \-.\C,  I  N  KKHI  N(. 


HANDILY  PACE:    BIPLANE:       AB.E-A    1.648    5«  rT 
/PAN  -  UPPER  PLANt  WO  FT  -LOWIS.70F-*       CHORD  IOF7 


SHADED      AHCAS 
INDICATE     T»^ 
LOWfcR    PLANE- 


-A    ( 

)     A" 

CUBfUCl 

N-C-1    HYING  50  AT        AEtA 
tE  PlANt  \16  FT  -LOWtB.96  T-T 

J« 
CHORD    1 

FT 
2PT 

BIPLANE-  WITH   AWING    ARtA    Of-    10.00O 

./•PAN,  E>OTH  PLANtS.    171     FT        CHORD     28*7  « INCH  fry 


-iow  Can  We  Distribute  the  10,000  Square   Feet  of  Wing  Surface   Required   to   Lift   20 

Tons  of  Useful  Load? 


For  commercial  success  the  aeroplane  should 
e  Iniilt  to  carry  'JO  tons  of  useful  load. 

How  can  the  1O.IMM)  square  feet  of  wing  siir- 

e  required  to  lift  this  useful  load  lie  dis- 
rihutedf  It  would  he  absolutely  out  of  the 
uestioii  to  think  of  constructing  a  monoplane 
f  that  area.  Since  experiments  have  shown 
ie  most  desirable  winj;  proportion  is  to  have 
ie  spun  ahout  six  times  the  width  of  the  plane, 
r  in  other  words,  the  aspect  ratio  should  be 
bout  »>  to  1.  This  would  mean  that  in  order 

obtain  1(1.000  square  feet  of  surface  in  a 
lonoplane.  its  surface  would  have  to  be  244.8 
.•et  in  length  or  span,  and  40.8  feet  in  width 
r  chord. 

1 1'  the  same  area  is  to  be  obtained  in  a  biplane, 
rvinjr  the  .same  aspect  ratio  or  span  to 
hord  relation,  our  span  would  be  171  feet  and 
'tc  chord  -_'K..)  feet.  It  is  claimed  tHht  when 
ir faces  are  superimposed  the  full  lift  is  not  ob- 
lined  from  all  the  planes.  In  the  triplane  the 
ft  of  the  middle  wing  is  somewhat  decreased 
eeause  of  the  interference  of  the  plane  above 
nd  the  plane  below.  Some  engineers  have 
ven  gone  so  far  as  to  claim  that  the  middle 


plane  ^i\es  practically  no  lift  whatever.  This. 
of  course,  is  a  mistaken  notion.  Provided  that 
the  gap  between  the  planes  is  great  enough,  each 
of  the  planes  is  as  efficient  as  a  monoplane  sur- 
face. The  middle  plane  gives  a  decreased  lift 
when  the  adjacent  planes  are  placed  too  close  to 
it,  for  then  the  air  flow  is  interfered  with.  It 
remains  with  the  designers  of  triplancs  and  mul- 
tiplanes to  determine  the  aenxlynamical  effi- 
ciency of  the  aerofoil. 

Structural  advantages  are  to  be  had  in  tri- 
plane and  multiplane  combinations  and  very 
often  the  disadvantages  resulting  in  decreased 
efficiency  of  the  wings  are  more  than  offset  by 
the  structural  advantages  gained. 

If  we  tried  to  build  a  triplane  with   lo.mm 
feet  of  surface  it  would  have  to  be  close  ' 
feet  high. 

Here  comes  the  difficult  problems  of  landing. 
We  recall  that  the  Avro  triplane  at  the  lioston- 
Harvard  Meet,  September.  1910,  had  the  tend- 
ency of  toppling  over  at  the  least  cause.  That 
machine  established  a  traditional  prejudice 
against  triplanes  and  quadruplanes.  But  the 
height  of  aeroplanes  has  gone  up ;  and  although 


16 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


MONOPLANE- 

./PAN  244.5  ?! 
CHORD  40.8  F-T 


BIPLANE 

yPAN  171   PI 
CHOP-D 


3   PLANED 


4  PLANE./1 


5   PLANE-./" 


-E  -i-  E-E 


./•PAN   141     CHORD  23.5        /PAN  121.6     CHORD  203       JPM  109.2    CHOBD  18.2 

COMBINED  MONOPLANES   AND   BIPLANES 


5     PLANED 


7  PLANED1 


12  PLANED 


8  PLANED 

J'PAN  86.4    CHORD  14.4 


109.2    CHORD  18.2       ./TAN  92.4    CHOBD  19-4       ./PAN  7O.2    CHORP  11.7 

COMBINED     BIPLANES  AND 


TPlPLANf 

./•PAN  141  PT 
CHOBD  23.5  PT 


10   PLANty 


Z5    PLANtv/- 


JTAN  92. A     CHQKP  15.4         yPAN  77. 4     CHORD   12-9         ./'PAN  48.6     CHORP  B.l 

COMBINED  TRIPLANLV   &  QUADRUPLANE,/1 


17     PLANED 


QUADP.UPLANE 

yPAN  121.8  PT 
CHOBD   20.3  PT 


15  PLANE,/ 

63     CHORD  10.5 


-/"PAN  48.6      CHORD  8.1  ./TAN   59.4  F-T      CHORD    9-9  FT 

MULTIPLANE    COMBINATIONS 


the  prejudice  still  remains,  the  height  of  aero- 
planes is  increasing  year  by  year.  The  Porte 
triplane  is  over  27  ft.  6  in.  high;  the  Caproni  tri- 
plane  is  over  19  ft.  high,  the  Gotha-Zeppelin  is 
21  ft.  high,  the  Voisin  triplanes  are  18  and  19 
ft.  high  respectively,  the  Handley-Pages  are 
from  18  to  20  ft.  high;  the  Curtiss  NC  is  24% 
ft.  high. 

Such  a  machine  as* proposed  would  possess  a 
high  center  of  gravity  and  would  be  apt  to  over- 
turn on  landing,  due  to  inertia,  unless  the  body 
and  lever  arm  were  of  sufficient  length  to  coun- 
teract this  force. 

Then  also  we  must  consider  that  it  would 
necessitate  a  hangar  of  unusual  structure  to 
properly  house  such  a  machine.  This  is  one  of 
the  allied  problems  which  come  up  when  unusual 
planes  are  contemplated. 

When  Handley-Page  built  his  large  biplane, 


in  1916,  and  adopted  a  ten-foot  chord,  instead 
of  the  conventional  6%-foot  chord,  he  started  a 
new  development.  He  demonstrated  the  possi- 
bility of  using  a  greater  chord  to  solve  the  prob- 
lem of  building  larger  planes  without  going  into 
extreme  wing  spans  or  excessive  heights. 

But  while  adopting  a  greater  chord  may  be  a 
partial  solution  in  building  an  aeroplane  with 
5000  square  feet  of  wing  surface,  it  does  not 
afford  -a  practical  solution  in  building  a  plane 
with  10,000  square  feet  of  surface. 

We- must,  therefore,  turn  to  new  sources  for 
solution  of  the  problem  of  distributing  10,000 
square  feet  of  wing  surface  in  order  to  lift  the 
20  tons  of  useful  load  referred  to  above. 

The  following  table  has  been  prepared  to 
show  how  an  area  of  10,000  square  feet  can  be 
disposed  and  divided  into  from  1  to  25  planes, 
each  preserving  the  proper  aspect  ratio. 


STATTS  OF  AIM'TIKI)  AKU<  >.\  ATTIC   F..\  ( .  I  M  .1  .H  I  \(i 

Area  Distribution,  Wings  with  Aspect  Ratio 
of  6  to   1 


17 


\iinilirr 
of 

Surl 

1 


-. 

•i 

III 
11 
19 
l.t 
11 
l.i 

u 
II 

I- 
II 

.'II 
.'I 


lull 

Siirf.Kv 
(M|.  ft.) 

III.IHNI 
.'..IHMI 

-VVMI 
.'.INK) 
I.'.  '.i. 
l.l> 

1,111 

1.IMMI 


...... 

-- 
,,, 

400 

4JV 

I  il 
416 
400 


l'h.ir.1 
(  f.,-1 , 

I-..' 

I'M, 
I.-..J 
111 

11.7 
ll.li 

Kl.l 
9.9 
9.6 

9.1 

-.i 

8.4 
8.3 
8.1 


Sp.ni 

i;i  .u 
iii.n 
ttU 

-i  n 

7u..' 

H  i 

MM, 

39.4 
57.6 

.'.I. i. 
41.0 

IM 

i-  ii 


It  is  noticed  that  in  flic  larger  aeroplanes  the 
aspect  ratio  tends  to  increase.  Fur  example, 
tin  Handli-y-1'a.ne  lias  a  ratio  of  10  for  the  up- 


plane  and  7  Tor  tin-  lower.  Tins  IN  true  als,, 
of  tin-  Caproni  Triplaiu-  \\lu-n-  the  aspect  ratio 
of  all  three  planes  is  aliout  Id.  Where  :,  on-atrr 
aspect  ratio  i<,  under  consideration  land  the 
trend  of  design  in  lary;rr  machines  leads  us  to 
the  adoption  of  greater  spam  a  different  tal.l. 
of  dinieiisions.  would,  of  course,  he  necessary, 
hut  the  one  sho\\n  ahove  ^i\<s  us  a  working 
liasis.  n| mi  \\hieh  calculations  of  a  more  exact- 
ing nature  may  he  founded. 

Relation  of  Gap  to  Chord 

Tlie  proper  relation  of  gap  to  chord  is 
greatly  a  matter  of  opinion.  Authorities  .i 
agn-c  on  how  close  win<;s  can  IK-  placed  without 
mutual  interference.  This  is  true  c\en  in  tin- 
rase  of  triplanes.  Manufacturers  like  Caproni. 
Aimstron^-Whitworth.  Hoe  and  Curtiss  ha\e 
conducted  experiments  with  triplancs  and  ((uad- 
rupIaiH-s.  hut  it  is  a  fact  that  very  little  aerody- 
namical data  is  available  covering  the  results  of 
tests  on  triplanes.  quadruplancs,  and  multi- 
planes. 

Kvt-n  at  this  late  date  many  people  will  con- 
tend that  triplanes  and  <|iiadruplancs  are  ineffi- 
cient hecaiise  the  middle  wings  do  not  lift.  It 


I    PLANf      JPAN   344.6  PT        CHOB.D  40.8  F-T 


2    PL*Nfr.T 


I7I.O 


CHO&D     38.5  ft 


3  PLANED  ^PAN  I4I.O 
CHODD    E3.5  PT 


8  PLIkNtr  /PAN  S6.4 
CMOD.D    W.4  PT 


L 


_L 


15  PLANE/  /PAN    63  PT 
CMOCD    KX5  r! 


4  PLANt/  /PAX  121.6  f-T    CHORD    2O.3  PT 


18 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Latest  type  of  Voisin  4  motored  900  h.p.  Biplane. 


is  hardly  necessary  to  point  out  that  if  the  mid- 
dle wings  do  not  lift,  the  trouble  must  be  that 
the  engineer  did  not  get  the  best  proportion  of 
gap  to  chord. 

Another  reason  why  a  loss  in  efficiency  may 
be  found  in  triplanes  and  multiplanes  is  that  no 
modification  of  the  wing  curve  may  have  been 
made  according  to  its  particular  application. 
When  a  monoplane  wing  section  is  to  be  em- 
ployed in  a  biplane  arrangement,  changes  might 
be  made  in  the  contour  of  the  under  surface  of 
the  upper  plane,  and  the  upper  surface  of  the 
lower  plane.  In  the  triplane,  alterations  should 
be  made  as  in  the  biplane  and  furthermore,  both 
upper  and  lower  surfaces  of  the  middle  plane 


must  be  changed  to  coordinate  with  the  plane 
below. 

With  experiments  along  this  line,  more  effi- 
ciency can  be  expected  in  the  multiplane  of  the 
future.  It  is  not  to  be  wondered  at  that  so 
little  success  has  met  the  efforts  of  designers 
who  sought  to  employ  a  "universal  wing  curve," 
having,  they  believed,  a  constant  effect  whether 
used  as  a  monoplane,  biplane,  or  triplane,  de- 
ducting 5  or  10f/r  for  multiplane  inefficiency 
without  suspecting  that  an  alteration  of  the 
curves  would  give  more  desirable  results. 

It  may  be  found  that  altered  wing  curves 
permit  of  closer  spacing  between  planes,  tend- 
ing to  cut  down  both  the  weight  of  interplane 


The  DeH.-17,  a  twin  motored  Tractor  Biplane.  This  machine  has  been  designed  for  high  speed  passenger  and  freight 
service.  The  saloon  will  accommodate  14  passengers,  each  comfortably  seated,  having  a  clear  view  in  all  directions,  and  free 
to  move  about.  Lavatory  accommodations  are  also  provided.  The  motors  are  of  600  h.p.  each.  The  machine  is  capable  of 
making  a  speed  of  125  m.p.h.  and  has  a  radius  of  400  to  500  miles  at  full  speed.  It  can  climb  to  10,000  feet  in  15  minutes. 


STATl'S  OF  APPI.IKI)  AERONAUTIC   KMJ1N  KKH1NC 


Thr   1  r.  n.  li  C.iiiilrini  "   \i-rnlui>  "  wliidi  is  ,  Mi-nun:  p  i~.  HL-.  -r.  U-t«,,-n   I'.irU  Mini   l.iniiliin.     Thr    .'  'nu|.ir>   arc  rnrlosed  in  strcain- 

Im.  .1   n.i.-.-IIrs   in  .iril.-r  In  drrrrusi-  Hi.-  resistance. 


struts  ;iii(l  bracing  :iiiil  tin-  resistance  they  pre- 

.SCllt. 


of  finding  proper  relation  between  the  gap  and 
chord,  distances  between  sets  of  planes  and  of 
the  reduction  to  a  minimum  of  parasite  resist- 


Tandem   Planes   Represent   the   Solution         a  nee. 


Thr    lirst     possible    solution    tllilt     suggests    it- 

sell'  is  that  tin-  10.000  square  I'cct  of  wing  sur- 
face lie  distributed  in  Tandem  Plant's.  Hut 
what  should  the  Tandem  Planes  he?  Mono- 
planes' Hi|.  lanes.'  Multij  Liu's? 

Tlie  first  noteworthy  experime  its  with  Tan- 
dem plains  \\cre  made  by  Sainucl  P.  Lan^ley. 
Sinee'then  a  nuinhi-r  of  experiments  have  been 
made  with  tandem  planes  hut  few  of  the  experi- 
menters have  had  the  opportunity  of  testing 
triplanes  and  ffettin^  aenulynamieal  data  so  as 
to  ascertain  the  relative  efficiency  of  Tandem 
1  Manes.  This  is  a  tremendous  field  and  here 
the  aeronautic  engineers  will  have  to  find  the 
correct  relation  between  surfaces  that  are  dis- 
posed one  above  the  other  and  in  Tandem 
Planes,  the  distances  between  the  planes  or 
groups  of  planes.  If  three  or  more  sets  of 
planes  are  to  he  used,  then  the  problems  multi- 
ply. for.  then  will  come  in  again  the  problem 


Problems   of  Trussing   and   Bracing 

The  employment  of  many  lifting  surfaces, 
either  superimposed  or  adjacent,  will  necessi- 
tate new  structural  methods.  In  this  field,  our 
engineers  and  bridge  builders  can  help  us.  \\Y 
need  the  simplest  forms  of  structural  stiffening. 
in  order  not  to  create  too  much  parasite  resist- 
ance. By  dividing  up  our  wing  area  into  many 
small  planes,  the  loading  on  each  plane  will  IK.' 
comparatively  light,  and  consequently  it  would 
seem  that  a  light  but  sufficiently  safe  structure 
can  l>e  used  for  these  wings.  (See  in  Appen- 
dix article  on  the  Evolution  of  Aeroplane  Wing 
Trussing.) 

Body  Construction 

We  will  assume  that  the  distribution  of  the 
10.000  square  feet  of  wing  area  necessary  to  lift 


\  C.iunt  Hriti-li  Flyintr  Boat,  driven  by  three  motors  a(rfrrr(tatin(f  HMHI  li.p.  Thfc  boat  wa*  used  by  the  British  at  Helip.l.ui.l 
I.itrlit  for  patrol  duty  It  lias  a  larfre  rruisin(r  radius  and  rnn  carry  a  considerable  load.  A  reconstructed  plane  of  thin  type 
will  tnaki-  a  jrixHl  type  of  commercial  passenp-r  and  freight  carrier. 


The    interior    of   a    Handlev-Pape,    electrically   heated    passenger  carrying  biplane  used  for  regular  passenger  carrying  air  lines 


The  "  Braemar"  Mark  II  Bristol  Triplane,  driven  by  four  400-h.p.  Liberty  Engines.     It  has  a  wing  span  of  82  feet,  and  carries  a 

useful    load   of  8,000   Ibs. 
20 


STATl'S  OF  Al'I'I.IKl)  AKRON  ATTIC   KN<;  I  N  KKRI  Ni. 


llritMi  Ariiistn.ntf  WhiUnrth 
l.'ii.iilrii|,|.nit-  uill.  a  I  in  ti  |>  I 
i  ML'im-  It  is  ii  two  s.-atrr,  jfrnrral 
utility  lu.K-liiiif  ntiil  inakrs  a  sp«i'<l 
i  -I  in  |>.h.  nt  (rround  Irvrl.  This 
wait  onr  of  the  first  quadruplanes  to 
l.<  l.uilt. 


•JO  tons  o!'  cargo  has  been  successfully  worked 
out.  At  this  point  we  art-  confronted  liy  an- 
other serious  |>rol>Icm.  I  low  arc  we  going  *" 
construct  a  body  or  fuselage  for  this  Multi- 
plain-'  We  must  provide  spaces  for  the  cargo  in 
such  locations  as  to  make  them  readily  access- 
ible, and  at  the  same  time  to  make  the  moments 
ahout  the  center  of  gravity  of  the  whole  machine 
either  comparatively  small  or  else  nicely  cmial- 
i/.ed.  in  order  to  prevent  undesirable  flying  de- 
fects. The  problem  of  furl  storage  is  also  pres- 
ent. The  machine  would  be  multi-motored,  and 
the  location  of  these  motors  and  tin  ir  fuel  sup- 
plies will  involve  a  large  amount  of  careful  plan- 
ning. 

Furthermore,  if  our  plane  is  to  be  a  passenger 
carrier,  comfortable  (|iiarters  must  be  provided. 
Hire  again  \\e  must  try  to  emulate  the  stand- 


ards of  yacht  and  ship  builders.  We  should 
try  to  locate  our  passengers  so  that  they  could 
obtain  an  unimpaired  view,  since  the  latter  is 
of  the  supreme  joys  of  an  air  voyage. 

The  type  of  multiplane  will  also  involve  proh- 
l<  ins.  If  it  is  to  be  a  flying  boat  type,  it  must 
be  made  strong  and  seaworthy,  and  at  the  same 
time  not  unduly  heavy.  If  we  are  planning  a 
land  niaehine,  the  landing  gear  must  he  propor- 
tioned to  wi'hstand  the  heavy  loads  with  a  good 
factor  of  safety  and  yet  not  offer  too  mueh  air 
resistance  in  flight. 

There  follow  herewith  the  designs  and  details 
of  construction  of  practically  all  the  important 
types  of  aeroplanes  in  existence  to-day.  The 
engineer  is,  therefore,  enabled  to  compare  them 
and  see  what  the  l>e.st  aeronautic  engineering 
practice  of  different  countries  is. 


Sikorsky     I  i|i|ane    r<)ui|>|«-ci     with    4     Argus    motors    of   I4O    h.|>.   rnrli    was    tin-    |>n>tuty|H-    of   the    iiiiilliiituloriil    plane*. 


22 


TKXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


This  1917  Sikorsky  biplane  was  equipped  with  4  Renault  motors  of  -'-0  h.p.  each.     It  was  built  in   Russia. 


A  5-motored  German  Giant  Biplane.  In  the  nose  of  the  machine  is  an  engine  driving  a  tractor  screw.  The  other  four  en- 
gines are  mounted  in  tandem  sets  of  two.  A  machine  of  this  kind  represents  a  possible  type  of  commercial  aeroplane  of  the  im- 
mediate future.  However,  it  can  readily  be  seen  that  the  proportions  of  a  machine  of  this  lifting  capacity  are  approaching  a 
limit.  Some  other  method  of  distribution  of  the  aerofoil  surfaces  is  needed  to  obtain  a  still  greater  lift. 


A  view  of  the  Forward  nacelle  showing  the  covering  of  the 
front  motor,  the  radiator  mounting,  etc.  The  observers  have  an 
excellent  view,  both  ahead  and  behind. 


The  two  sets  of  tandem  motors  in  the  German  5-motor 
Biplane  are  mounted  on  long  engine  bearers.  They  dri 
their  propellers  through  gear  boxes.  The  cutting-out  of  t 
trailing  edges  of  the  wings  for  pusher  propeller  clearance 
thereby  avoided.  The  importance  of  using  geared  drive  f 
weight  carrying  aeroplanes  has  been  fully  demonstrated. 


CIIAI'TKH    II 


MULTI-MOTORED  AEROPLANES 


The  5-Motored  German   Biplane 

Complete  details  of  this  m.-irliinr  ;irc  not  axailable  at  the 
present  time.  Tin-  wreck  of  our  of  (lie  bombing  machines 
of  this  type  \x  is  can  fnlly  studied  by  members  of  (lie  Brit- 
ish Technical  Department  :iMil  :in  approximate  idea  of  its 
construction  xvas  obtained. 

Tin-  power  plants  are  arranged  as  follows:  In  the  nose 
nf  the  inachiiie  is  one  engine  drix  ing  n  tractor  screw.  On 
each  side  of  the  fuselage,  supported  by  the  wings,  is  a  long 
pair  of  engine  hearers,  carrying  two  engines  apiece,  which 
drive  tractor  and  pusher  screws,  in  a  manner  similar  to 
that  employed  in  the  earlier  designs  of  the  Russian  giant 
plane  constructed  by  Sikorsky  in  I!»IM. 

The  engines  used  are  the  Max  bach  300  h.p.  standard 
ti-cy Under  \ertical  type,  driving  the  propellers  through  a 
\-i>\  and  driving  shaft.  This  necessitates  the  employ- 
ment of  a  My  wheel  on  the  engine,  to  which  is  added  the 
female  portion  of  a  flexible  coupling. 

The  .rear  box  casing  consists  of  a  massive  aluminum 
casting  provided  with  four  feet  which  are  bolted  to  the 
engine  1  carers. 

Two  kinds  of  gear  boxes  are  employed.  These  differ 
only  in  oxer  all  dimensions  and  the  length  of  the  propeller 
shaft. 

The  larger  type  is  used  for  the  pusher  screw  in  order  to 
obviate  the  necessity  of  cutting  a  slice  out  of  the  trailing 
I  the  main  planes. 

In  each  case  the  gear  reduction  is  21 — 41. 

Plain  spur  pinions  are  used  having  a  pitch  of  22  mm. 
and  a  width  across  the  teeth  of  ~.">  mm.  The  diameter  of 
the  smaller  of  the  driving  pinions  is  162. .">  mm.,  and  that 
of  the  larger  pinion  282  mm. 

The  larger  pinion  is  considerably  dished,  but  the  web  is 
not  lightened  by  any  perforations. 

The  oxer-all  dimensions  of  the  longer  gear  box  is  as 
follows: 

I  .u-th.  Iii2.'>  mm. 
Hreadth.  673  mm. 
Height.  .">.'<;>  mm. 

The  driving  pinion  runs  on  two  large  diameter  roller 
bearings  carried  in  gunmetal  housings  supported  in  the 
inner  end  of  the  gear  box.  This  part  is  split  vertically, 
and  united  by  the  usual  transverse  bolts,  whilst  the  conical- 
shaped  portion  of  the  box  is  solid.  The  usual  oil-thrower 
of  helical  type  are  fitted. 


23 


At  its  outer  end  the  pinion  shaft  terminates  in  a  ring  of 
serrations  which  engage  with  serrations  provided  in  the 
male  portion  of  the  flexible  coupling,  these  two  parts  Ix-ing 
held  together  with  bolts  and  clamping  plates.  The  engine 
is  thus  close  up  against  the  gear  box.  in  contradistinction 
to  the  design  of  the  (-engine  power  plant.  There  i*  pmr- 
1 1<  ally  no  external  shaft  at  all.  The  larger  pinion  is 
mounted  on  a  hollow  shaft  of  !'.'  mm.  diameter,  carried  on 
roller  bearings  at  each  end  for  radial  load  and  furnish-  d 
at  the  nose  end  with  ball  thrust  hearings. 

In  the  shorter  type  of  gear  box  the  larger  pinion  shaft 
is  left  solid,  and  it  would  appear  that  the  gear  box  casing, 
instead  of  being  made  in  three  pieces,  is  made  in  two 
pieces,  i.e.,  the  whole  box  is  simply  split  vertically. 

The  smaller  pinion  shaft  projects  right  through  the  gear 
box,  and  at  its  outer  end  carries  a  projection  fitted  with  a 
small  ball  thrust  race.  This  projection  acts  as  a  drive  for 
the  oil  pump,  which  is  mounted  on  the  oil  radiator  used  in 
connection  with  each  gear  box. 

It  is  worthy  of  notice  that  the  German  designers  have 
fully  realized  the  importance  of  using  geared  engines  for 
weight  carrying  aeroplanes,  and  are  apparently  satisfied 
with  the  external  gear  box  principle,  although  in  this  case 
they  have  made  it  a  very  ponderous  affair.  Needless  to 
say,  a  great  amount  of  the  weight  could  have  been  saved 
if  12-eylinder  engines  had  l>ccn  used  instead  of  6-cylinder. 

The  weights*  of  the  gear  box  and  its  attachments  are  an 
follows: 

Gear  box,  long  type.  HO  Ibs. 

Fly  wheel  and  female  clutch,   11  Ibs. 

Male  clutch.  ;.  Ibs. 

Oil  radiator,  12"  L.  Ibs. 

This,  it  will  Ix'  seen,  represents,  an  additional  weight  of 
considerably  more  than  1  Ib.  |x-r  h.p. 

The  oil  radiator  used  in  conjunction  with  each  gear  box 
is  of  a  roughly  semi-circular  shape,  and  is  slung  under- 
neath the  main  transxerse  members  of  the  engine  bearer* 
so  that  it  comes  immediately  beneath  the  large  feet  of  the 
gear  box.  This  radiator  is  entirely  of  steel  construction, 
and  embraces  65  tubes  of  approximately  20  mm.  internal 
diameter.  These  are  expanded  and  sweated  into  the  end 
plates,  to  one  of  which  is  fitted  a  stout  flange,  against 
which  is  bolted  a  small  gcnr  pump  which  constantly  circu- 
lates the  oil  from  the  gear  box  case  through  the  radiator. 

This  gear  pump  is  driven  by  a  flexible  shaft  from  the 
small  pinion,  the  shaft  and  its  easing  being  in  all  respects 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


similar  to  those  employed  for  engine  revolution  counters. 
This  flexible  drive  is  taken  off  a  small  worm  gear. 

Underneath  the  oil  pump  of  the  gear  box  proper  an  elec- 
trical thermometer  is  fitted,  which  communicates  with  a 
dial  on  the  dashboard. 

It  is  a  little  difficult  to  see  what  object  can  be  served  by 
this  thermometer,  unless  it  be  to  indicate  the  desirability 
of  throttling  down  a  little  in  the  event  of  the  oil  getting 
unduly  hot,  as  there  is  no  apparent  means  of  controlling 
the  draught  of  air  through  the  oil  radiator. 

Fitted  on  each  gear  box  and  working  in  connection  with 
the  oil  circulation  is  a  filter.  This  is  provided  with  an 
aluminum  case  and  a  detachable  gauze  cylinder  through 
which  the  oil  passes. 

The  arrangement  of  the  gear  box  is  such  that  the  axis  of 
the  propeller  is  raised  about  220  mm.  above  that  of  the 
engine  crankshaft. 

The  construction  of  the  long  engine  bearers  is  not  with- 
out interest.  Each  bearer  consists  of  a  spruce  or  pine  cen- 
tral portion,  to  which  are  applied,  top  and  bottom,  five 
laminations  of  ash.  On  each  side  are  glued  panels  of 
3-ply,  about  Vs  in-  thick. 

The  engine  bearers  taper  sharply  at  each  end.  and 
are  strengthened  by  massive  steel  girders  under  each  gear- 
box. 

The  screws  revolve  at  approximately  half  the  speed  of 
the  engine,  and  having  therefore  a  moderately  light  cen- 
trifugal load  to  carry,  are  made  of  a  common  wood  that 
would  scarcely  be  safe  for  direct  driving  screws.  The 
diameter  is  K.'iO  meters  and  the  pitch  3.30,  for  the  pusher 
screw,  but  it  is  not  possible  to  state  whether  the  tractor 
screws  are  of  the  same  dimensions  and  pitch. 

The  construction  is  very  interesting;  each  screw  is  made 
of  17  laminations  of  what  appears  to  be  soft  pine,  and 
these  laminations  are  themselves  in  pieces,  and  do  not  run 
continuously  from  tip  to  tip.  They  are,  of  course,  slag- 
gered,  so  that  the  joints  in  successive  layers  do  not  coin- 
cide. Two  plies  of  very  thin  birch  veneer  are  wrapped 
round  the  blades.  The  grain  of  this  veneer  runs  across 
the  blade  instead  of  along  it.  It  is  difficult  to  say  from 
the  appearance  of  the  screw  whether  this  veneer  has  been 
put  on  in  the  form  of  2-ply  or  as  two  separate  layers,  one 
after  the  other. 

The  engine  control  consists  of  five  stout  steel  tubular 
levers.  The  levers  are  fitted  with  ratchets,  so  that  each 
one  can  be  operated  individually;  but  the  presence  of  the 
large-diameter  toothed  wheel  in  the  center  of  the  lever 
shaft  would  seem  to  indicate  that  all  five  levers  could, 
when  desired,  be  controlled  simultaneously. 

The  Douglas  type  of  engine,  carried  for  the  purpose  of 
driving  the  dynamo  of  the  wireless  and  heating  installa- 
tion, is  used.  The  engine  is  a  very  close  copv  of  the 
2%  h.p.  Douglas  and  is  made  by  Bosch.  The  flv  wheel 
is  furnished  with  radial  vanes  which  induce  a  draught, 
through  a  sheet-iron  casing,  and  directs  it  past  cowls  on 
to  the  cylinder  heads  and  valve  chests. 

The  generator  is  direct-driven  through  the  medium  of  a 
pack  of  flat  leaf  springs,  which  act  as  dogs  and  engage 
with  the  slots  on  the  fly  wheel  boss. 

An  apparent  transformer,  used  in  conjunction  with  the 
wireless  set,  was  also  in  use. 

The  tail  skid  of  the  machine  is  built  up  of  laminations  of 


MULTI-MOTORED  A  KUOl'l.A  \  ES 


25 


jisli  and  is  furnislu-il   with  :\  lieax  y    s|<  •<  1   slim-  .unl  .1   large 
unixersal  :itt;iflinii  lit. 

The  4-Motored  Voisin  Triplane 

In  order  to  axoid  eonstructiiii;  a  machim  •  >!  huge  pro- 
portions in  order  to  obtain  the  desired  lift,  tin-  French 
haxe  taken  a  step  in  tin1  riylit  direction  in  distributing  into 
thriv  planes  thr  necessary  aerofoil  ana. 

Tin-    Voisin    triplanes    .-in-    an    example    of    this    type    of 
machine.      They  arc  powered  with   four  motors,  operating 
in   a   manner   similar   to   those   on    the    Handle] 
chine.      The    tail    is    supported    liy    streamlined    oatn_ 
as  shown  in  tin-  illustration  In-low. 

The  4-Motored  Handley-Page  Biplane 


This  Iriijc  niai-hiiii-   was  designed   by    Mr.  Joseph   Hand- 

.11  Kn^lish  aeronautic  engineer  of  over  ten  v  ears' 

experience.      It   is  powered  with   four  Itolls-Koyce  or  Lib- 

erty  motors,  mounted   in   pairs.  one  liehind  the  other  and 

driving  tractor  and  pusher  screws. 

The  niacliiiie  is  capable  of  carrying  more  fuel  and  use- 
ful lo  .-id  than  would  In-  required  to  cross  tin-  Atlantic 
In  November.  l!Ms,  forty  p  isscngers  were  car- 
ricil  o\i  r  the  city  of  London  in  a  maeliine  of  this  type,  and 
a  month  later  a  flight  was  made  trout  London  to  Cairo 
and  from  Cairo  to  Delhi.  India.  These  demonstrations 
established  this  type  of  plane  as  a  longdistance  passenger 
and  mail  carrier. 

The  4-Motored  Sikorsky  Biplane 

The  originality  and  energy  of  the  Russian  aviator  and 
inventor.  Mr.  I.  I.  Sikorsky,  made  him  one  of  the  pioneers 
in  the  design  and  construction  of  huge,  multi-motored  bi- 
planes. 

In   the   sprinsr  of    1913,    his   first   giant   aeroplane   was 


ready   to  lake  the  air.       II.    called  it  the  "  Uiissi.m   Knight." 

In    general    arr  in-einent.    the    "  Kiiss,  HI     Knight"    was 

ch  iraeli  ri/t  d    ly     a     xery     hm^.    shallow     liody.    nliotit     IS) 

in-  It  rs  in   h  iiiilh.  nhoxe   which   the  cahin   portion   extended 

for  a  conaiderable  distance.     Tin    ~p.::i  ot  its  win^s  «  is 

'•'  rs    with   a   chord   of    :i   meters.      A    monoplane    tail 
and  four  vertical  rud.h  rs  constituted  the  (nil  units. 

The  cahin  portion  of  the  mai  him-  forms  the  most  inti  r- 
eslin;;  feature.  It  was  dixidrd  into  three  compartments. 
In  the  front  one  wen  t«..  s,  ,ts.  ..n.  on  e-i  h  sid,  (if  the 
cahin,  in  front  of  which  were  the  dual  controls.  \.ir 
mally  the  controls  on  the  hit  win-  the  main  ones,  and  in 
front  of  them  were  mounted  all  the  various  instruments. 
Between  the  two  s,,ts  was  an  open  space  hading  to  n 
door  opening  out  on  to  the  open  part  of  th<  hody  in  the 
extreme  n.-si  I-' nun  here  observations  could  l>e  made 
with  ease,  as  the  position  was  so  far  forward  ns  to  Ix  w.  II 
clear  of  all  obstructions.  For  use  at  night  n  searchlight 
was  placed  right  o:it  in  the  lx>w,  where  it  would  not  ila/./li- 
(lie  pilot  but  would  i'luminatc  the  landing  ground. 

The  central  portion  of  the  cabin  was  set  aside  for  the 
accommodation  of  pass,  M-,  rs  As  was  to  be  expected  in 
a  machine  so  elaborately  equipped,  the  passengers  were 
not  asked  to  si|ucc/c  into  seats  of  the  ordinary  bucket  type. 
Chairs,  well  upholstered  and  not  fixed  to  the  floor  were 
pi -iced  alongside  the  windows.  Communication  between 
passengers'  and  pilot's  cabins  was  by  means  of  a  glass 
door,  and  thus  any  passenger  could  walk  through  the 
pilot's  compartment  out  on  the  <>|>cn  front  portion  of  the 
body,  where  a  more  unobstructed  view  was  obtainable. 
From  illustrations,  the  doors  leading  out  into  the  open 
appear  to  be.  instead  of  sliding,  of  the  swinging  pattern. 
so  that  opening  them  against  the  pressure  of  the  air  may 
have  been  attended  with  some  difficulty. 

To  the  rear  of  the  passengers'  compartment  was  n  par- 
tition, with  a  door  leading  to  the  aft  cabin,  which  was 
divided  into  two  parts,  one  part  of  it  being  set  aside  for 
housing  spare  parts,  while  the  other  contained  a  sofa  on 


X    v- 

x 


The    t- toreil    Voisin    Tri|>liinc.     The    rec|iiire<l    aerofoil   nrcn   has   been   distrilmtril    into   tlirec    j. lanes,    therrl.y    l.riiniiiiL'    tlic 

|>ni|ii>rtii.iis   c,i    (lie   whole   machine   to   a    reasonable   standard.     'l"h<?  'necessary   vortical   surface  has   been   obtained   by    constructing 
:|   well  between   tile  two  sets  of  motors.     The   landing  gear  la  of  the  vehicle   tyjM-,  enabling  the  machine  to  easily   tr.m-l  over 
Die  ground. 


26 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


TWO   300  H.P.  MAYBACH  ENGINES 

_      SPANI; 


which  those  weary  of  the  journey  might  lie  down  and  rest. 
It  is  stated  that  the  cabin  walls  so  reduced  the  noise  of  the 
engines  that  conversation  could  be  carried  on  quite  com- 
fortably inside  the  cabin. 

In  front  the  body  rested  on  the  lower  main  plane,  which 
further  supported  the  four  Argus  motors  of  100  li.p.  each 
that  supplied  the  power.  At  first  these  four  motors  were 
mounted  in  pairs,  one  pair  on  each  side  of  the  body,  the 
front  one  driving  a  tractor  screw  and  the  rear  one  a  pro- 
peller. Later  a  different  arrangement  was  tried  by  which 
the  four  engines  were  all  placed  on  the  leading  edge,  two 
on  each  side  of  the  fuselage,  and  each  driving  a  tractor 
screw.  Later  again  the  two  outer  engines  were  removed 
altogether,  and  the  machine  flew  quite  well  with  the  re- 
maining two.  After  having  done  a  considerable  amount  of 
flying  and  established  a  world's  record  for  passenger 
carrying — 1  hour  54  minutes  with  pilot  and  seven  pas- 
sengers — •  the  "  Russian  Knight  "  came  to  an  untimely 
end  through  a  machine  flying  overhead  shedding  its  en- 
gine, which  crashed  through  the  wings  of  the  "  Russian 
Knight." 

Immediately  afterwards,  Sikorsky  began  to  construct  an 


Three  views  of  the  German  Zcpji 

improved  type  of  giant.  He  finished  his  machine  in  De- 
cember, 1913,  but  to  his  great  astonishment  it  refused  to 
fly.  After  making  certain  alterations  he  succeeded  in  get- 
ting a  very  good  flight  out  of  it.  This  second  giant  was 
the  famous  "  Ilia  Mourometz."  The  span  of  its  wing  was 
thirty-two  meters  with  a  chord  of  three  meters.  The 
"  Ilia  Mourometz  "  presented  a  very  peculiar  appearance. 
The  front  of  the  body  was  flush  with  the  front  of  the 
wings.  The  body  and  the  under-carriage  were  constructed 
on  an  entirely  different  design  to  that  of  the  "  Russian 
Knight."  The  body  instead  of  being  completely  made  of 
three-ply  wood  was  merely  webbed  with  three-ply  and 
covered  with  canvas.  It  had  a  series  of  cabins  which  ex- 
tended for  a  little  more  than  half  its  length,  after  which 
a  gangway  led  to  the  extremity  of  the  tail,  where  a  short 
ladder  and  trapdoor  gave  entrance  to  the  tail  deck.  This 
deck  was  very  small  and  was  only  used  by  the  mechanics 
to  regulate  the  tail  plane  and  the  rudder  wires.  The  main 
deck  was  in  the  middle  of  the  body  and  it  was  constructed 
to  carry  machine-guns  and  searchlights.  A  third  deck 
was  fixed  to  the  under-carriage  and  here,  too,  there  was 
room  for  a  machine-gun  or  a  searchlight.  The  aeroplane 


MULTI-MOTORED  . \KKO1M..\NKS 


'27 


YO   300  HP.  MAYBACH   ENGINES 

:ET 


TIVO  MECHANICS 

3OO  H.R  MAYBACH  ENGINE 

GUNNER 


3OOH.RM4YBACH 
TWO  MACHINE   GUNS 


MACHINE  6UN 


—  LENGTH  72  FEET 


lin   (-motored  Moiiiliiiii:  Biplane. 

had  fi)iir  landing  wlicels.  Sikorsky  succeeded  in  getting 
much  better  n-sults  from  his  second  than  from  his  first 
giant  and  during  the  spring  of  191  -I  he  made  many  note- 
worthy Highls.  The  power  plant  consisted  of  four  engines 
cl<M  loped  up  to  five  hundred  and  twenty  h.p.  The  speed 
of  the  aeroplane  was  about  one  hundred  and  five  kilo- 
im-trrs  nn  hour  and  it  could  carry  a  load  of  two  and  a  half 
tons,  though  as  a  matter  of  fact  it  rarely  carried  more 
tli.m  one  and  three  quarter  tons. 

During  the  past  two  years,  giant  biplanes  of  the  Sikor- 
sky type  have  been  built  in  England,  and  equipped  with 
Rolls-Royce  motors;  they  have  done  excellent  work. 

The  4-Motored  Zeppelin  Biplane 

The  principal  details  of  this  machine  were  obtained  by 
a  group  of  engineers  from  the  examination  of  a  bomber 
brought  down  in  France. 

Tin-  pi  me  is  equipped  with  four  Maybach  engines  deliv- 
ering a  total  of  1-.JOO  h.p.  Each  motor  is  independent. 
All  are  placed  at  the  same  level  and  in  pairs.  They  are 
set  i.p  one  behind  the  other.  The  front  ones  are  tractors 


and  the  rear  ones  are  pushers.  F.ach  motor  is  placed  be- 
tween two  braces.  Half  of  the  length  on  the  motor  ex- 
ti  ink  behind  these  braces,  and  half  ahead  of  them. 

In  order  to  bring  the  center  of  gravity  of  the  machine 
sufficiently  far  forward,  the  weight  of  the  two  engines  is 
massed  towards  the  leading  edge  of  the  main  plane;  by 
driving  the  screws  through  shafts  and  reduction  gears,  tin- 
necessity  of  cutting  away  large  sections  from  the  planes  to 
give  room  for  the  rear  propellers  has  been  avoided.  Tin- 
two  engines  are  placed  close  together,  so  that  the  rear 
motor  is  some  little  distance  away  from  its  screw.  The 
forward  engine  is,  however,  mounted  close  up  to  the  tractor 
screw. 

The  employment  of  shafts  and  reduction  gears  nece-si- 
tates  fly  wheels  on  the  engines.  These  are  I  ntrtrrs  in 
diameter,  and  are  made  of  cast  iron.  The  tubular  driving 
shafts  between  the  fly  wheel  and  the  gear  box  are  furnished 
with  flexible  leather  couplings.  These  are  of  a  novel  ty|x-, 
and  consist  of  a  male  and  female  drum,  each  furnished  with 
circumferential  notches,  between  which  are  interposed  a 
series  of  flat  leather  strips.  The  female  drum  forms  part 
of  the  flv  wheel. 


Avion  geant  Zeppelin 

(Echelle   1/150<|. 


AVION   GEANT  ALLEMAND 


Bombing  Plane.     The  4-Motored  Zeppelin  Biplane.     Drawings  by  Jean  Lagorgette. 

The  ribs  of  the  lower  wings  and  lower  elevators  are  shown  in  dotted  lines,  also  the  rudders.  To  the  left  and  out  of  the 
fuselage  figures  three  and  four  show  the  diameter  of  the  transversal  struts.  The  upper  wings  are  in  reality  45cm.  out  of  center. 
B  and  I  are  transversal  frames.  In  G  frame  the  wing  longeron  is  placed  somewhat  underneath  the  position  it  occupies  in  !•',  and 
it  replaces  the  tube  cross  bracing  above  frames  E  to  H.  The  dotted  lines  indicate  longitudinal  beams,  c  is  the  sectional  lon- 
geron of  the  fuselage,  e  is  a  section  of  the  corner  angle  of  the  fuselage  in  the  angle  of  the  longeron. 


M./r  i 


? Longueur  tot*U..2 


Clponmirt    Li 

t  •    „       S.fO     ff-W 

\'.DO    ' 


A  side  view  of  the  /eppelin  Bomber.  The  upper  wings  are  really  out  of  center  at  the  rear  about  45  cm.  The  angle  of  in- 
cidence is  such  that  the  struts  are  at  right  angles  to  the  chord.  The  propeller  and  motors  are  about  1-2  cm.  back.  The  ribs  of 
the  central  section  are  extended  into  the  legs  of  AH  of  the  cockpit.  There  are  two  elevators  in  similar  directions  and  the  cent  nil 
section  comprises  a  large  triangle  besides  the  lateral  planes,  the  inside  apex  of  which  forms  a  semi-ellipse.  The  parts  B-A  in 
the  sketch  may  be  taken  to  pieces  without  spoiling  the  main  part  of  the  machine. 

28 


MlI/ri-MOTOKKl)   Al.KOIM.ANKS 


\^^^^ 

i  *t  wni  n  i  vr/*,*  *, 

if  ttt  r*<  M.IHI  t 
.H,*t  it* 

-  ,„-  \QIAPHAWT*   JHfftfft 

\n>** 


.        :  •          . 


Dia,;rii.iiiiiatic   view    of  lln-  constrii;  lion  of  thr  /.cp|tclin    l-motorcd 


Iliplimc. 


Tlir  ue.-tr  l»i\  consists  ot  a  casing  i>f  aluminum,  prov  ithcl 

With   ffiiiljll^   f',11-.. 

Mi-ni-.ilh  c. it-li  i;r.-ir  t-.iM  i>  .-i  >in;ill  r:uli:itor  fur  cotilin)! 
tin-  liilirir.'itin-z  "il  cirt'ul.-ili  il  tlinri^li  tin-  rnu'ir-.  This 
r-nli-ittir  t-Kii-ists  of  ;i  tl:it  si-nii-cirt-ulnr  tank,  fitted  with 
iruni-ro-.i-  (T.-ITI-M  r^t-  Cil't--.  .it  fairly  Inrj;c  ilinmctcr  ( about 
-,'n  nun.)  in  a  ni.uiiie  r  similar  to  that  of  n  honryromh  ratli- 
ntur.  A  pump  Miiiiintcd  at  the  linsr  of  the  radiator  is  also 
ftirnislii-d  with  an  electrical  thermometer,  giving  a  reading 
on  i  ili  il  in  tin-  ciu-kpit. 

i-iii;ini'  !•<  fitted  with  a  self  starting  arrangement  of 

the  tv|x-  usually  fitted  tt>  Mavhat-h  motors.      The  exhaust 

pipe    may    he   closed    l>y    mean-,    of    a    shutter,    and    all    the 

cylinders  can   l»    filled    with  gas   from   the  carburettor   by 

-   of  a   large   hand-pump,   for   whi;-h   pur|x>se  all   the 

\al\es  are  held  open.      \\'ht  n   these  valves  are  closed,  and 

the   starting  magneto  operatitl.   the   engine    tires   aiiil   con- 

tinni-s  running.      Kach  engine  has  its  own  radiator,  whh'h 

is  in  united  directly  above  it.  and  supported  by  stnts  and 

'ires  at  a  point  about  half-way  In'tween  the  top  and 

^i    planes.      These    radiators   are   of   the    usual    type. 

They  are  rectangular  in  shape,  with  their  greater  length 

placed  hori/.ontally,  and  the  radiating  surface  consists  of 

i  zig-zag  tubes  placed  vertically. 

The  engine  hearers  consist  of  stout  ash  spars,  reinforeed 
with  mulii-ply  wood.  The  engine  controls  appear  to  be 
made  chicHy  of  ash  and  covered  with  a  thin  veneer. 

Wing  Construction 

Tin  spars  are  built  up  very  elaborately  in  sections,  and 
consisting  of  no  less  than  seven  sections  of  spruce,  rein- 
forced with  multi-ply  on  each  side,  and  finally  carefully 
•it!  with  doped  fabric. 

The  spars  of  the  lower  wings  are  continuous,  that  is  to 


they  run  right  across  tile  center  section  of  the  fusel- 
age, to  the  longerons  of  which  they  are  secured,  contrary 
to  the  usual  practice,  in  which  special  compression  mem- 
bers, forming  part  of  the  fuselage  construction,  are  em- 
ployed. The  wing  surface,  both  upper  and  lower,  is  di- 
vided into  three  sections,  of  which  the  middle  section  ex- 
tends to  the  engine  mountings  on  each  side.  Tl.i  spars  in 
this  section  are  both  at  right  angles  to  the  axis  of  the 
fuselage.  At  each  side  of  the  middle  section  the  leading 
edge  of  the  wings  is  boldly  swept  back  as  well  as  tapered. 
The  rear  spars  of  the  wings,  together  with  those  of  the 
center  section,  form  a  straight  line  from  wing-tip  to  wing- 
tip,  but  the  front  spars  are  swept  back. 

Tin   ribs  are  built  up,  and  of  girder  form. 

Between  the  leading  edge  and  the  leading  spar,  numer- 

0  is  extra  ribs  occur  in  addition  to  the  main  ribs.      Internal 
bracing  against  drag  takes  the  form  of  steel  tubular  com- 
pression members  and  steel  cables,  the  former  being  placet! 
at  a  point  coincident   with   the  attachment  of  each   inter- 
plane  strut.     An  additional  bracing  is  installed,  of  which 
the  compression  member  consists  of  a  double  rib  placed 
half-way   between   the    struts.      In   each  case  the   bracing 
wires  pass  obliquely  right  through  the  spars. 

The  ribs  are  mounted  parallel  to  the  line  of  flight. 
The  dis|>osal  of  the  spars  is  as  follows: 

Top  Plant  — 

Leading  eclfre  to  center  of  leading  spar. . .   1  ft.  9i/t  in. 

Distance  lietween  centers  of  spurs    i  ft.  ~'/»in. 

Trailing  edjre  to  center  of  rear  mnin  spar  5  ft. 

lloltom  Plant  — 

1  .ratlin?  edfrr  to  center  of  lending  spur. . .    1  ft.  TV,  in. 
Distances  U'twern  centers  of  m.-iin   spurs.    5  ft.  I  in. 

Trnilinjr  edge  to  center  of  rear  main  spar  5  ft.  (approximately). 

The  trailing  edge  of  this  aeroplane  was  too  badly  dam- 
aged to  permit  of  this  measurement  being  given  accurately. 


30 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


fofa/e 


>,t  "00 


F,0.  3  eH.  -  Avion  ««.n,  Zm.ll*  -  E^^,- ^n^Ti"^n^^^^^  ^'^  ^^'  """  ~  ""*  "'  ""' 

Giant  Zeppelin  Aeroplane,     al  -  duralumin;  b  — wood;  c- cable;  f  -  steel  cable;  g- sheath;  t  — tubing. 


Between  the  interplane  struts  the  rear  spars  are  thinned 
down  in  width,  but  their  depth  remains  practically  constant 
from  root  to  tip.  Such  tapering  as  exists  is  so  arranged 
as  to  promote  a  decided  wash-out  of  the  angle  of  incidence 
near  the  tip.  This  is  done  by  tapering  the  front  spar  on 
its  upper  edge,  and  the  rear  spar  on  its  lower  edge. 

Ailerons 

These  are  on  the  top  planes  only,  and  are  provided  with 
a  framework  of  steel  tubing.  They  are  not  balanced,  and 
the  controls  are  led  in  the  usual  manner  through  the  bot- 
tom plane  from  the  aileron  lever. 

The  span  of  each  aileron  is  22  ft.  5  in.,  and  the  chord 
3  ft.  4  in. 

Inter-plane  Struts 

These  are  of  large-diameter  steel  tube,  covered  in  with 
a  streamline  fairing  consisting  of  three-ply  mounted  on  a 
light  rib-work  of  wood. 


Bracing 

The  attachment  of  the  bracing  cables  to  the  spars  is 
somewhat  similar  to  the  bracing  of  the  Fokker  fuselage; 
that  is  to  say,  the  wires,  instead  of  being  anchored  at  each 
end  to  an  eyebolt,  are  double,  and  are  looped  round  the 
spar,  to  which  is  fixed  a  grooved  channel-piece  for  the 
reception  of  the  cable.  It  is  difficult  to  see  that  any  ad- 
vantage is  gained  by  this  arrangement. 

Tail  Unit 

A  biplane  tail,  somewhat  similar  to  that  of  the  Handley- 
Page,  is  fitted.  The  fixed  tail  planes,  the  angle  of  inci- 
dence of  which  can  be  adjusted  through  small  limits,  are 
of  wooden  construction,  and  have  the  following  dimen- 


Span  each  side  of  fuselage   12  ft.    4  in. 

Chord    (average)    4  ft.  10  in. 

Gap    6ft.    9ys  in. 


The  Bristol  Bomber  Triplane  Type  "Braemar"  with  4  Puma  engines.     The  motors  are  mounted  in  tandem  pairs.     Ailerons   are 

fitted  to  the  ends  of  the  two  upper  planes  only. 


MULTI-MOTORED  AKKoi'LANKS 


virw  of  the  liristol  1-inotorccl   llraemar  Tripl.uie.    The  continuous  middle  wing  over  the  fuselage  is  an  interesting  feature. 


Elevators 

Tin  se  arc  fitted  to  both  tlir  top  .-mil  bottom  tail  planes. 
and  ari  ..(  .iliiiiiiiiiiin  construction.  tin-  rilis.  being  of  girder 
form,  sunn  what  similar  in  construction  to  tin  ribs  of  the 
mum  planes.  Tin  ili  'valors  ari-  not  balanced;  the  top  and 
l)ottom  delators.  are  titled  with  independent  control  levers. 
lint  arc  prcsiimalilv  operated  together  from  the  control 
.stick.  Their  dimensions  arc  ax  follows: 


S|...n     ..............................................  -"»«.  6  in. 

Choril    ;.t    lip    .......................................    -'ft.  tin. 

Chord    lit   center    ....................................    I  fl.  «  i". 

Fins 

There  are  three  fins;  two  outer  ones  forming  interplanr 
struts,  and  an  inm-r  central  one  of  triangular  shape. 


Rudders 

The  framework  of  these  orirans  is  hiiilt  up  of  aluminum. 
There  is  also  a  quadrant  nt  the  foot  of  the  rudder  posts  by 
means  of  which  the\  are  operated;  each  rudder  |K>st  it 
fitted  with  ball  bearings,  both  top  and  bottom. 

Undercarriage 

Beneath  each  engine  section  is  an  undercarriage  consist- 
ing of  a  massive  axle  fitted  with  four  wheels  at  each  end. 
This  axle  is  attached  by  india-rubber  shock  absorbers  to 
the  tubular  steel  V-struts  which  form  extensions  of  the 
engine  bearer  struts.  A  third  undercarriage  is  mounted 
under  the  forward  pnrt  of  the  fuselage,  and  consists  of  an 
axle  with  one  pair  of  wheels. 


Photograph   of   the    famous    IV    llnviland    10,   which   is   being   used  in  the  London  to  Paris  passenger  service.    This  machine  is 
equipped  with  two  Koll.s-Hoyce  motors,  and  has  a  maximum  speed  of  128  miles  per  hour. 


32 


MULTI-MOTORED  .\KK<  HM.ANK 


The    I       >     \  ,.\    i  urti--    No.    I.   (ir-t    to   cro-s    tin-     \tl.intic 


The  U.  S.   Navy-Curtiss  No.  4  Transatlantic  Seaplane 


Tlii-  \(  Type  of  Hying  boats  constructed  liy  tin-  Cnrtiss 
Cn!ii|i.iiiy.  represent-  strictly  original  American  elcvelop- 
IM.  tit.  Tin-  design  was  initial,  d  in  the  Fall  of  I!H7  by 
Rear  Ailmiral  I).  \V.  Taylor,  chii-f  constructor  of  the 
I  S.  \.-i\y.  The  big  boats  were  designed  for  weight 
carrying  and  it  was  intended  to  use  them  in  eomlritini; 
the  submarine  menace  which  had  assumed  alarmini;  pro 
portions  in  1!>18.  The  NC-1  was  completed  and  given 
her  trials  in  October.  I'.US.  Since  that  time  the  NC-2, 
\i  '•'.  and  NC-1-  followed  in  quirk  succession. 

Fully  loaded  the  machine  weighs  28,000  Ibs.  and  when 
empty  (  hut  including  radiator  water  nnd  fixed  instru- 
ments .-mil  equipment)  l;>,K7t-  Ihs.  The  useful  load  avail 
aMe  for  crew,  supplies  and  fuel  is.  therefore,  12,126  Ibs. 
or  oxer  I-:!  per  cent.  This  useful  load  may  be  put  into 
fuel,  freight,  etc..  in  any  proportion  desired.  For  an 
endurance  High)  there  would  be  food,  v/ater,  signal  lights. 
spare  parts,  and  miscellaneous  equipment  (52 }  Ibs.),  oil 
(7.10  Ihs.).  and  gasoline  (!K5.»0  Ibs.).  This  should  suf- 
fice for  a  flight  of  1100  sea  miles.  The  radio  outfit  is  of 
sufficient  power  to  communicate  with  ships  2OO  miles  away. 
The  radio  telephone  would  be  used  to  talk  to  other  planes 
in  the  formation  or  within  x'5  miles. 

The   principal  dimensions  of  all  the  NC  Machines  are 
as  follows: 

General  Dimensions 


Span,   upper    plane    1 36  ft.  0  in. 

Spun,  lower   plane   91  ft.  0  In. 

Chord    I.'  ft.  0  in. 

Gap,    maximum    13  ft.  6  in. 

Gap,  minimum   I  -1  ft.  0  in. 

I-ength  overall   68  ft.  3%  In. 

Height  overall    34  ft.  5%  In. 


Areas 

Main  planes   (including  aileron-) 

Ailerons    , 

Stiiliilizrrs    

Rudders     

Elevators      

Fins 


Of.  /I 


905 


40 
79 


Angles 


tn  hull    .  . 
Kn^ine-  to  hull    . 
Staliiliftcr    to   hull 
Dihedral,  upper   .  . 
Dihedral,    lower 


3" 
0* 

•r 

0" 
3s 


Weights 

Pound, 

Machine   empty    !5,H?i 

Fully    lomlrd     iHjOOO 

Csefiil   lo.id    I 

Weight  per  l>.h.p 17.i 

Tank  Capacities 


Gruvitv      

'/of/on* 
.                      91 

Fuel     

1.800 

Oil    . 

160 

Performance 

Knoll 

Speed   rnnge  for  IHflM  Ilis 74-58 

Speed   range  for  J4/WO  Ibs 84-53 

Main  Planes 

Considerable  research  and  experiment  was  necessary  to 
determine  the  best  disposition  of  material  to  adopt  for 
wings  of  this  si/e.  The  R.  A.  F.  6  curve  is  used.  The 
structural  weight  of  the  completed  wings  is  only  1 '  .. 
pounds  per  square  foot,  and  they  can  carry  a  load  of  11.7 
pounds. 

Wing  spars  are  of  spruce,  box  section.  Ribs  are  made 
up  of  spruce  cap  strips  tied  by  a  system  of  vertical  and 
diagonal  strips  of  spruce. 

Each  rib  weighs  but  '2fi  ounces.  On  test  they  were 
required  to  carry  a  proof  sand  load  of  1AO  pounds  for 
21  hours  without  showing  signs  of  weakness. 

The  leading  edges  of  main  planes  are  hinged  to  permit 
accessibility  to  the  aileron  control  cables,  which  run  con- 
cealed in  the  wing. 

Interplanc  struts  arc  of  unusual  construction.  Tliev 
are  of  box  section  spruce,  faired  off  to  a  streamline  shape 
by  -tiff  fibre.  To  reduce  any  tendency  of  the  struts  to 


34 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


with  4  Liberty  motors 


bow  under  load,  the  middle  points  are  connected  by  steel 
cable. 

The  metal  fittings  where  struts  and  wires  are  fastened 
to  the  wings  presented  a  serious  problem.  The  forces  to 
be  taken  care  of  were  so  large  that  it  was  necessary  to 
abandon  the  usual  methods  of  the  aeroplane  builder  and 
adopt  those  of  the  bridge  designer.  All  forces  acting  at 
a  joint  pass  through  a  common  center.  In  this  case,  as 
in  a  pin  bridge,  the  forces  are  all  applied  to  a  large  hol- 
low bolt  at  the  center  of  the  wing  beam.  In  the  design 
of  the  metal  fittings  to  reduce  the  amount  of  metal  needed, 
it  was  decided  to  employ  a  special  alloy  steel  of  150,000 
Ibs.  per  square  inch  tensile  strength.  To  increase  bear- 
ing areas,  bolts  and  pins  are  made  of  large  diameter  but 
hollow. 

The  upper  plane  is  in  three  sections ;  center  section  25 
ft.  6Vi>  in.  in  span.  Lower  plane  in  four  sections ;  inner 
sections  of  the  lower  wing  are  built  into  hull.  There  is 
a  clearance  of  ^4  inch  between  outer  and  inner  plane  sec- 
tions. 

Outer  lower  sections  have  a  3°  dihedral;  elsewhere 
plane  sections  are  in  flat  span. 

Ends  of  struts  supporting  middle  engines  are  centered 
50%  inches  apart.  Between  these  struts  the  middle  en- 
gines are  located  6  ft.  10  3/16  in.  above  the  center  line 
of  the  front  wing  beam.  The  center  line  of  the  top  front 
•wing  beam  is  located  6  ft.  7  15/16  in.  above  center  line  of 
nacelle. 

The  outer  engine  nacelles  are  centered  10  ft.  6  11/16  in. 
from  the  middle  of  the  machine,  and  5  ft.  5  1/16  in.  above 
the  top  of  the  front  wing  beam. 

The  center  engines  are  located  2  ft.  0  in.  higher  than 
the  outer  engines. 

The  span  of  the  upper  plane  not  including  the  aileron 
extensions  is  114  ft.  Ailerons  on  the  upper  plane  are  36 


ft.  long.  Chord  43  in.  At  the  balanced  portion  the 
chord  is  6  ft.  1  in.  Balanced  portion  extends  6  ft.  beyond 
the  end  of  upper  rear  main  wing  beam.  Ends  of  ailerons 
project  15  ft.  beyond  lower  plane. 

Chord  of  main  planes  12  ft.  Forward  main  wing  beam 
centered  16]/i  in.  from  leading  edge;  beams  center  84  in. 
apart;  trailing  edge  431/-;  in.  from  center  of  rear  beam. 

Hull 

The  hull  or  boat  proper  is  44  ft.  8%  in.  long  by  10  feet 
beam.  The  bottom  is  a  double  plank  Vee  with  a  single 
step,  somewhat  similar  in  form  to  the  standard  N'avy 
pontoon  for  smaller  seaplanes.  Five  bulkheads  divide  the 
hull  into  six  watertight  compartments,  with  watertight 
doors  in  a  wing  passage  for  access.  The  forward  com- 
partment has  a  cockpit  for  the  lookout  and  navigator.  In 
the  next  compartment  are  seated  side  by  side  the  principal 
pilot,  or  aviator,  and  his  assistant.  Next  comes  a  com- 
partment for  the  members  of  the  crew  off  watch  to  rest 
or  sleep.  After  this  are  two  compartments  containing  the 
gasoline  tanks  (where  a  mechanician  is  in  attendance) 
and  finally  a  space  for  the  radio  man  and  his  apparatus. 
The  minimum  crew  consists  of  five  men,  but  normally  a 
relief  crew  could  be  carried  in  addition. 

The  hull  is  designed  to  have  an  easy  flaring  bow  so  that 
it  can  be  driven  through  a  seaway  to  get  up  the  speed 
necessary  to  take  the  air  and  a  strong  Vee  bottom  to 
cushion  the  shock  of  landing  on  the  water. 

The  combination  of  great  strengtli  to  stand  rough  water 
with  the  light  weight  required  was  a  delicate  compromise, 
and  it  is  believed  that  a  remarkable. result  has  been  ob- 
tained in  this  design.  The  bare  hull,  as  completed  by 
the  yacht  builder  and  ready  for  installation  of  equipment, 
weighs  only  2800  Ibs.,  yet  the  displacement  is  28,000  Ibs., 
or  one-tenth  of  a  pound  of  boat  per  pound  of  displace- 


MULTI-MOTORED  . \KKO1M..\\K 


Tin-    Nl     I,   transatlantic  t\  |ie  seaplane,  powered   liy    four  l.ilierly   motors 


m<  nt.  Tliis  lightness  of  construction  was  attained  liy  :i 
car,  III!  selection  ;ili(l  distribution  of  mat,  rials. 

Tin-  keel  is  of  Sitka  spruce,  as  is  tin-  planking.  Longi- 
tudinal strength  is  thru  liy  two  girders  cif  spruce  braced 
with  sti-t-1  wire.  To  insure  w  ater  tightness  and  yet  keep 
tin-  planking  Ihin.  linn  is  a  layer  of  muslin  set  in  marine 
between  the  two  piles  of  planking. 

The  Hull  is  H  ft.  S-,  in.  in  01,  rail  length.  Step  is 
loeated  _'T  ft.  8:! ,  in.  from  the  bow.  The  stern  rises  in 
a  straight  line  from  the  step  in  a  total  height  of  H  '  •_.  in. 
The  hull  has  a  maximum  depth  of  7  ft.  5"^  in.,  and  a 
maximum  width  of  10  ft.  The  leading  edge  of  upper 
main  plane  is  located  18  ft.  2  in.  from  the  bow. 

Tail  Group 

The  biplane  tail   is  carried  on   three   hollow   spruce   nut- 

Front  beam  of  upper  horizontal  stabilizer  is  MO 

ft.    I  I  '  |   in.   from   trailing  edge  of  main   plane.      Gap  be- 

tail  planes.  ;i  ft.  3  in.     The  single  lower  outrigger 

from   the   hull   to  the   lower  stabilizer   is   attached  to   the 

stahili/.i  r  at  a  point   10  ft.   11   in.  above  the  lowest  point 

the  hull. 

Span  of  upper  elevator.  .'17  ft.  11  in.  The  lower  sta- 
bili/.er  is  32  ft.  in  span.  Knds  of  upper  elevator  project 
5  ft.  I  1  '  L.  in.  beyond  the  lower  stabilizer.  The  balanced 
portion  of  tile  elevators  is  (i  ft.  ~>  ill.  in  width. 

Tin-  upper  stabilizer  is  :t  I   ft.  in  span.      I.ower  stabilizer 

in  span.     Chord  of  both  stabilizers  .5  ft.  6  in. 
Vertical    tins    between   stabilizer   planes    are   loeated   at 
ends   of   lower   stabilizer.      From   these    tins,    rudders   are 
Wnged,  interconnected  to  balanced  rudder  situated  at  the 
middle  of  tail  plane. 

The  tail  planes  have  a  positive  incidence  angle  of  2°. 

Controls 

The  steering  and  control  in  the  air  are  arranged  in 
principle  exactly  as  in  a  small  aeroplane,  but  it  was  not 
;s\-  problem  to  arrange  that  this  1  1-ton  boat  could 
be  handled  with  ease  by  one  man.  To  obtain  easy  opera- 
tion, each  control  surface  was  balanced  in  accordance  with 
expi  rim,  nts  made  in  a  wind  tunnel  on  a  scale  model.  The 


operating  cables  were  run  through  ball  Ix'aring  pulleys, 
and  all  avoidable  friction  eliminated.  Finally,  the  entire 
craft  was  so  balanced  that  the  center  of  gravity  of  all 
weights  came  at  the  resultant  center  of  lift  of  all  lifting 
surfaces  and  at  the  tail  surfaces  so  adjusted  that  the  ma- 
chine would  be  inherently  stable  in  flight.  As  a  result, 
the  boat  will  fly  herself  and  will  continue  on  her  course 
without  the  constant  attention  of  the  pilot.  When  he 
wishes  to  change  course,  however,  a  slight  movement  of 
the  controls  is  .sufficient  to  swing  the  boat  promptly. 
There  is  provision,  however,  for  an  assistant  to  the  pilot 
to  relieve  him  in  rough  air  if  he  becomes  fatigued  or 
wishes  to  leave  his  post  to  move  about  the  boat. 

Engines 

The  four  Liberty  engines  which  drive  the  boat  are 
mounted  between  the  wings.  At  MM)  brake  h.p.  per  engine, 
the  maximum  power  is  1600  h.p..  or  with  the  full  load 
of  28,000  pounds,  17.3  pounds  carried  per  h.p.  One  en- 
gine is  mounted  with  a  tractor  pro|«-ller  on  each  side  of 
the  center  line,  and  on  the  center  line  the  two  remaining 
engines  are  mounted  in  tandem,  or  one  behind  the  other. 
The  front  engine  has  a  tractor  propeller  and  the  rear 
engine  a  pusher  propeller.  This  arrangement  of  engines 
is  novel  and  has  the  advantage  of  concentrating  weights 
near  the  center  of  the  boat  so  that  it  can  be  manoeuvred 
more  easily  in  the  air. 

A  feature  that  is  new  in  this  boat  is  the  use  of  welded 
aluminum  tanks  for  gasoline.  There  are  nine  v2O()-gallon 
tanks  made  of  sheet  aluminum  with  welded  seams.  F.ach 
tank  weighs  but  7<i  11s..  or  .:C.  Ib.  per  gallon  of  contents. 
about  one-half  the  weight  of  the  usual  sheet  steel  or  copper 
tank. 

The  face  of  the  radiator  for  outer  engines  is  I.",  ft 
in.  from  the  bow.  The  face  of  the  radiator  for  the  for- 
ward middle  engine  is  lit  in.  back  of  the  face  of  other 
radiators.  The  (enter  line  of  central  nacelle  is  6  ft. 
5  1/16  in.  above  the  deck  of  the  hull.  Above  outer  inter- 
plane  strut  the  center  line  of  front  wing  beam  is  located 
13  in.  above  the  deck  of  the  hull. 


V 


THE  CAPBONI 

TYPE    CA-4    1915 

TBIPLANE 

_/c».l«    of  meter-/- 
'  ' i S — 


36 


MULTI-MOTORED  A  KROIM.ANKS 


I  riphiin1,  c.ijialilr  of  carr\  ini: 


ful  loud  of  fi,(»<)9  |I>S. 


The  Caproni  Bombing  Triplane  Type  CA-4 


The  (  aproni  triplanc  represents  n  type  designed  and 
built  by  the  famous  Italian  constructor  since  1915.  This 
iii.-tchine  was  err  atcd  at  th.it  time  for  the  night  bombing 
of  important  military  and  naval  bases,  railroad  stations 
and  war  plants. 

There   are   three  motors,  distributed   on   the   two    fuse 
lages  and   on   the  central   nacelle.     The  central   motor   is 
tor  a  pusher  propeller,  while  the  two  lateral  motors  have 
i  i.  li  a  tractor.      Both  tractors  turn  in  the  same  direction. 

Fuselages  and  nacelle  are  attached  to  the  spars  of  the 
middle  wing.  The  center  wing  section,  lower  plane,  holds 
the  bomb  rack.  This  bomb-dropping  apparatus  was  also 
devised  by  Kngineer  Caproni. 

Normally  the  crew  of  the  maehine  consists  of  two  pi- 
lot,, seated  side  by  side,  as  it  is  usual  with  the  Caproni 
bombing  planes,  a  gunner  in  the  front  nacelle  cock  pit. 
who  operates  a  1 '  ..-inch  gun  and  two  Fiat  machine  guns, 
coupled  on  the  same  mount.  The  front  gunner  also  oper- 
ates a  searchlight  of  the  Sautter-Marie  type.  The  rear 
defence  is  entrusted  to  two  gunners,  each  of  whom  is 
seated  in  one  of  the  fuselages;  they  also  handle  Fiat  ma- 
chine guns  coupled  on  the  same  mount. 

F.ach  of  the  five  men  can  move   from  one  part  of  the 
maehine  to  another.      Between  the  central  naeelle  and  the 
fuselages    on    the    middle    wing   a    passage    covered    with 
r  wood  is  installed  for  this  purpose. 

The  bomb  sight  and  the  five  handles  controlling  the 
bomb  rack  are  operated  by  the  pilot  on  the  right-hand 
si  at. 

The  CA-l  triplanc  has  been  successively  equipped  with 


three  different  ty|«'s  of  motors.  At  first  three  Isotta- 
Fraschini  8-cylinder  (vertical)  2-10/250  h.p.  engines  were 
used;  it  was  later  equipped  with  three  Fiat  A  14-Bis  6- 
cylinder  (vertical)  engines,  and  finally  three  Libcrty-12 
engines.  Navy  ty|x-  (low  compression)  were  adopted. 

With  an  aggregated  useful  military  load  of  OOOO  Ibg. 
the  performance  of  this  triplanc,  equipped  with  Liberty 
engines,  have  IN-CII.  especially  in  climbing,  considerably 
better  than  those  obtained  with  the  other  two  types  of 
motors.  In  the  official  tests,  at  full  load  and  fully  armed. 
a  speed  of  98  ni.p.h.,  registered  at  65fiO  feet,  was  reached. 
The  average  rates  of  climbing  attained  with  Liberty  mo- 
tors at  full  military  loads  were: 


frrt  in  li  minutes 
6,560  fret  in  II  minutes 
10,000  fret  in  .'.•  minutes 

The  ceiling  is  at  about  16,000  feet. 

The  total  weight  of  the  machine,  empty,  is  11,100  Ibs. 
With  full  military  load  the  machine  weighs  17,7ml  Ibs. 

With  a  complete  fuel  load  of  550  gallons,  the  bomb 
rack  is  supposed  to  be  loaded  with  2500  Ibs.  of  bombs. 
but  practically  in  almost  all  bombing  raids  the  load  of 
bombs  exceeded  SOOO  Ibs. 

The  following  is  a  table  of  the  general  specifications. 

General  Eimensions 

Overall  wing  span  at  trailing  (edge)    ...........  96  ft.  6  in. 

Overall  height  to  top  of  aileron,  lever  in  nornml 

position    .....................................  20  ft.  8  in. 

Overall   length    .................................   *-'  ft.  II  in. 

Chord    .........................................     6  ft  11%  In. 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


A  Caproni  3-motored   Biplane  in  flight.     The  central  pusher  propeller,  and   the  tail  construction  can  readily  be  seen.    Span,  76 
ft.  9  in.     Chord,  9  ft.     Gap,  8  ft.  9  in.     Over-all  height,  14  ft.  9  in.     Over-all  length,  40  ft.  9  in.     Engines,  3  Liberty  400  h.p. 

Gap  7  ft.  13i/2  in.  Main  Planes 

Gap  -r-  Chord    .  £ach  of  t,)e  three  pjanes  ig  bu0t  up  in  seyen  wing  sec. 

Areas  tions.     The  corresponding  sections  in  upper,  middle  and 

EACH  lower  wings  are  equal  in  length.     The  wing  spars  are  of 

SECTIOX  ToT'Y'        box  beam  section.     The  ribs,  double  ribs  and  box  ribs  are 

Upper,  middle  and  lower  center  section '1.413  U5.240       in  white-wood  and  ash   (cap-strip).      Between  rib  and  rib 

Upper,  middle   and   lower   inner   intermediate  the  wing  spars  are  wrapped  with  strong  linen.     The  con- 
section    91.589  549.534      nection  between  the  two  subsequent  sections   is  obtained 

Upper,  middle   and   lower  outer   intermediate  wjt],  t]le  male  and  female  box-fitting  system. 

section  91.589  549.534  m,        ,        •.    .       ,.        .»  . .       .         ,.       £   ..          .  ~    -. 

The  chord  is.  for  the  entire  length  of  the  wings.  6  ft. 

Upper,  middle  and  lower  outer  section 130.282  781.692 

Aileron  area    37.810     226.863       J 1  %  m.      The  covering  is  of  linen,  nailed  on  the  rib  cap- 
strips    and   on   the    leading   and   trailing   edges.     On    the 

Total    area     2,222.86:        linen,  above  and  below  the  wing,  maple  batten  strips  are 

Rudder     26.943       80.829       screwed  in  correspondence  to  the  ribs. 

Stabilizer 109.752  . 

Elevator  81.614  *or  tne  mterplane  struts,  ash,  spruce  and  seamless  steel 

tubes  are  used.     Some  of  the  struts  have  adjustable  ends. 
Detailed  Dimensions  The  bracing  is,  as  usual,  with  steel  cables  and  wires. 

Upper,  middle  and  lower  center  section  length . .     5  ft.  6%4  in.  Gasoline  System 
Upper,    middle    and    lower    inner    intermediate 

section  length   13  ft.  iylfl  in.  The  gasoline  is  supplied  by  three  tanks  disposed ;  two, 

Upper,  middle  and  lower  outer  intermediate  sec-  one  in  each  of  the  fuselages  and  one  in  the  nacelle.      Three 

tion   length    1    f  t.  1%  0  in.  wind-driven   centrifugal   pumps   pump   the   gasoline    from 

Upper,  middle  and  lower  outer  section  length.         Wft  %  in.  ^  ^  to   &  ^^  ^.^r,   and   from   this   to   the 

Aileron  ...                                         •!     19 ft.  4i$8 to.  carburetors   of  the  three  motors.     The  pilots   have   close 

Stabilizer   length .34  ft.  li%2  in.  at  hand  the  devices  necessary   for  the  regulation  of  the 

Stabilizer  breadth   3  ft.  12%,j  in.  gasoline  pressure.     For  the  testing  of  the  motors  on  the 

Elevator  length  J    Mil  8U?  i  ground  two  small  gravity  tanks  are  provided;   these  are 

Elevator  breadth   ..     1ft.  l%\n.  '  excluded  from  the  circuit  while  the  machine  is  in  flight. 

Front  strut  height   (average)    7  ft.  3^'fl  in.  Each  of  the  three  tanks  is  divided  in  three  compartments. 

Rear  strut  height   (average)    7  ft.  8i%2  in.  and  at  the  bottom  of  each  of  said  compartments  a  check 

valve  is  applied,  this  valve  working  so  as  to  avoid   that 
in  the  event  one  of  the  compartments  is  shelled -the  gnso- 

ctT-r  wing,  c'7d  •/  I I  de£-  S0  min'      line  in  the  undamaged  compartments  should  leak  through 

Stabilizer   chord — minimum    3  deg.  ,  ,  , 

Stabilizer  chord-maximum 8  deg.  the  hole  bored  m  the  damaged  one. 

Motor  inclination 2  deg.  Chassis 

Stagger    0  deg. 

Sweepback   0  deg.  The  landing  gear  is  of  a  special  Caproni   design  and 

Dihedral   0  deg.  very  robust.     The  two  M-struts  are  of  laminated  ash  and 


MULTI-MOTORED  .\KKOIM..\NKS 


A  (':i|ir<>iii  hyilroaeroplime  cquip|tcil   with  three   l-'int  imitors  of  :K»>  h.|>.  mch. 


spruce,  wrapped  with  strong  cam -is  f  ihrie.  The  chassis 
carries  on  r-irh  side  one  front  .-mil  on<-  rear  a\le;  these 
avlcs  nre  attached  to  the  rh.-i-.sis  by  means  of  shock  ab- 
sorlx-r  rulilii-r  curd  .-mil  rods  fastened  at  the  other  end  in 
n  universal  joint,  so  as  to  adsorb  whatever  oscillation  the 
maehine  IM.IV  make  in  taxing  or  landing.  Kach  of  the 
front  axles  carries  two  double  wheels,  one  on  each  side 
of  the  M  strut.  The  chassis  is  braced  in  the  usual  man- 
ner with  double  steel  cables. 

Nacelle 

Tin-  nacelle  is  perfectly  streamlined  (dirigible  form). 
Two  main  longerons  with  compression  steel  tube  struts 
bet  u  i  en  them  and  diagonal  steel  brace  wire  and  cables 
form  the  frame  on  which  a  set  of  ribs  of  appropriate  de- 
sign are  fastened.  The  outer  edge  of  the  rilis  determine 
the  shape  of  the  nacelle.  Hirch  veneer  and  walnut  are 
employed  in  the  construction  of  these  ribs,  said  construc- 
tion In  -ing  of  a  manner  similar  to  that  employed  for  .similar 
elements  of  rtyin^  bo-its.  The  front  of  the  nacelle,  upper 
part,  is  formed  by  :i  cowling  made  of  plywood  with  in- 
terposed layers  of  fabric. 

The  two  pilots  are  seated  back  of  the  front  gunner. 
1'chind,  they  h.ive  a  gasoline  tank,  and  before  them  a  large 
dasbl-o-ird  for  the  instruments,  while  between  them  thev 


have  •  board  for  the  controls  i  gas.  spnrk  and  altitude  ad- 
justage)  for  the  three  engines.  The  gasoline  system  i» 
controlled  by  various  cocks  and  a  special  distributor,  all 
disposed  in  such  a  manner  as  to  render  them  easily  acces- 
sible to  either  of  pilots.  In  the  rear  of  the  gas  tank, 
which  is  of  the  same  circular  section  that  the  nacelle  has 
in  that  tract,  there  is  a  short  path  that  allows  the  mechanic 
free  access  to  the  rear  motor.  The  engine  bed  in  con- 
veniently braced  with  adjustable  steel  tubes  and  steel 
braces.  The  rear  part  of  the  nacelle  around  the  engine 
is  also  cowled.  For  the  remaining  parts  linen  and  veneer 
are  used. 

Fuselages 

The  fuselages  are  flat-sided  and  of  the  usual  construc- 
tion with  four  ash  longerons,  and  between  them  compres- 
sion struts,  steel  cables  and  wire  bracing.  All  the  fittings, 
to  which  the  diagonals  are  fastened,  can  be  manufactured 
with  the  same  set  of  dies.  They  are  extremely  simple 
and  light  in  weight,  without  welding  or  bracing,  and  are 
attached  without  drilling  the  longerons.  The  front  end 
of  the  fuselage  around  the  motor  is  aluminum  cowled.  A 
gas  tank  is  placed  in  the  rear  of  the  motor,  and  an  oil 
tank  under  it.  At  a  short  distance  from  the  trailing  edge 
of  the  middle  wing  a  seat  for  the  rear  gunner,  with  the 


The  Ameriran-maile  Caproni,  equipped  with  three   l.iherly  motors 


40 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


A  Caproni  hydroaeroplane  equipped  with  three  Fiat   A. -1-2  motors  rated  at  300  h.p.  eaeh.     The  Caproni  Biplane  has  also  been  suc- 
cessfully used  in  naval  work.     For  this  purpose  twin  pontoons  have  been  fitted  to  the  lower  plane,  with  suitable  attaching  braces. 


usual  arrangement  for  machine  guns  and  ammunition,  is 
installed.  From  the  height  of  the  gunner's  seat  to  the 
rear  end  the  fuselages  are  linen  covered.  A  Pensuti  tail 
skid  with  shock  absorber  is  at  the  end  of  each  fuselage. 

Control  Surfaces 

As  on  all  Caproni  bombing  planes,  the  stabilizer,  ele- 
vator, rudders  and  ailerons  are  of  steel  tubes.  The  tail 
surfaces  are  very  ample,  as  can  be  observed  from  the  di- 
mensions given.  The  stabilizer  is  solidly  braced  to  the 
fuselage  by  means  of  cables  and  steel  tube  struts.  It 
bears  the  three  characteristic  vertical  rudders.  The  ailer- 
ons are  six  in  number,  one  at  each  of  the  ends  of  the  three 
wings. 

As  also  on  the  other  Caproni  bombers,  dual  control  is 
fitted  so  that  the  plane  can  be  controlled  by  either  pilot  at 
will.  The  control  system  for  ailerons  and  elevator  is  a 
combination  of  the  wheel  and  stick  method;  the  vertical 
rudders  are  controlled  by  a  foot  bar  of  the  usual  type. 

For  emergency  use,  the  pilot  on  the  left  also  operates 
a  hand  pump,  sufficient  to  feed  the  three  motors  by  pump- 
ing from  the  central  tank.  Each  motor  has  its  own  oil 
tank  and  a  small  radiator  for  the  cooling  of  the  oil. 

The  lateral  motors  have  a  nose  radiator,  fastened  on 
the  same  beams  forming  the  engine  bed.  The  central  mo- 
tor has  two  radiators,  high,  narrow  and  streamlined,  each 
placed  at  the  two  rear  interplane  struts  between  the  cen- 
ter wing  sections,  middle  and  upper  plane.  All  the  ra- 
diators are  of  the  honeycomb  type,  and  equipped  with 
shutters. 


Lighting  and  Heating 

The  lighting  systems  for  navigation,  signalling  and 
landing,  and  the  heating  system  for  the  crew  are  fed  by 
a  wind-driven  generator  of  one  kilowatt,  combined  with  a 
large  storage  battery. 

Instruments 

The  instruments  are  all  set  in  a  large  dashboard  in 
front  of  the  pilots.  Besides  the  usual  standard  instru- 
ments for  navigation,  motor  and  radiator  control,  each 
pilot  has  a  Pensuti  Air  Speed  Indicator.  Some  machines 
are  also  equipped  with  an  Absolute  Speed  Indicator. 


CAP12ON1 


Left  —  One   of  the  two  tail   skids.     The   skid   itself   is   of   ash, 

wrapped  with  linen  and  shod  with  a  metal  shoe. 

Right- — One    of   the    two   landing   chassis    units,   composed    of 

four  wheels  with  double  rims  and  double  tires. 


MULTI-MOTORED  . \KKori..\NKS 


II 


•,  \ 


pcll.-rs      Hi'-  hull  has  a  (in  ami  two  steps.     This  Up,-  of  boat  was  much  used  for  patrol  duly. 


Curtiss   H-16-A   Flying   Boat 


Tin  II  -Mi  A  is  :i  t«  in-i-iiiiiin-d  M-aplaiic  with  a  flying- 
l>oat  hull,  usin^  trai-tor  propellers.  The  pilot  and  ob- 
scner  .-in-  seated  in  a  cockpit  about  half-way  ln-twrrn  the 
linw  mil  tin-  winjjs.  where  they  have  an  e\ei  Hi  lit  view. 
The  11  li!  is  also  fitted  with  a  gunner's  cockpit  the  same 
as  tin  IIS  :.  In  addition,  a  wirrlrss  opi-rator  is  rarricd 
"nside  the  hull  just  forward  of  the  wings  and  hark  of  tin- 
pilots.  Ali-ilt  tin-  winiis  an  additional  nun  ring  is  fitted 
COM  rim;  tin  arc  of  tin-  al'ovr  and  between  tlie  wings  and 
tin-  tail  controls  and  to  take  care  of  the  region  to  the  rear- 
and  l»  low  tin-  tail  .-ontrols;  gun  mounts  are  also  fitted. 
swinjiini:  «i\  brackets  through  side  doors  in  the  hull.  The 
hoinh  near  is  opi-ratrd  from  the  forward  gunner's  eoekpit 
and  four  lioinli-.  wi-n-  rarrii-d.  two  under  either  wing.  This 
typi-  of  boat  proved  very  MTV  in-able. 

General  Dimensions 

Win?  S))«n  —  I'pprr   Plum-    98  ft.  6%  in. 

^|>.in  -  l.owrr    I'lnnr    68  ft.  11%  in. 

Di-ptli  ..f  \V  in);  Chonl    84<%4   In. 

ti.-ip  iM'twrrn   XVinjr-   Sfi^ili  In. 

..  r     Nun.- 

,,f  Mm-hini-  ovrrull   46  ft.   l»%o  in. 

M.-i-lit  of  MarliiiH-  overall   17  ft.  8%  in. 

i-  of  Incidence   4  dejrrees 

Dihrilnil    Anfflr    1  degree 

•  luu-k      None 

\Vint'    Curv  •    R.   A.   F.   No.  6 

lli.ri/.Mital   -it.'iliilixer — Anple  of  Incldenrr   ...  2  degrees  pos. 

Areas 

I'pper   (without    Ailrrons)    616.2  sq.  ft. 

I.i  wrr     4-13.1   sq.  ft. 

.is     131    sq.    ft. 

Horizontal    -ital.iliwr    108   sq.ft. 

Vertical    St  il.iliier     31.1  sq.  ft 

•or-       58.4   sq.    ft. 

Kudili  r     J7.9   sq.    ft. 

nl*       ?4  sq.    ft. 

Totnl  Sui)|H)rnii)f  Surface    1.190J  sq.  ft. 


(welfrht  carried  per  MJ.  ft.  of  support-  8.S4  lb«. 

in|r   surfaci-)    

Londinir  (per  H.  H.  I'.)    15.42  Ihs. 

Weights 

Net  Wei(rht  —  Mnrhine  Kinpty   i;.'i:,i;  ll.s. 

Cross  Wright        Mnrhine  nn<l   Ixi«d    IO.I7J   Ihs. 

fseful    Ix>n<l    :»..'.>(!  Ihs. 

Fuel    and   oil    I^.T   Ihs. 

Crew    ««i  Ihs. 

load    .  .    1.029  Ihs. 


Totnl      :Wlfi  Ihg. 

Performance 

Speed  —  Minimum—  Horizontal  Klipht  9.5  miles  per  hour 
Sprnl — Minimum  Horizontal  Kli(rht  j.i  miles  per  hour 
Climhin)!  S|M-«1  I.OOO  fret  In  10  minutes 

Motors 

2  Liberty-  1-'  cylinder.  Vre.   Four-Stroke  Cycle   Water    cooled 

Horse    I'nwer    (rarh    motor  IMO)    660 

Weight    per   rated    I  lorsc   I'ower    2,55 

Bore  and  Stroke   5x7  in. 

Furl  Consumption  pi-r  birr  (loth  motors)   62.8  gals. 

Fuel   Tank    Capacity    300  gals. 

Oil   Capacity    Provided    10  gals. 

Fi»-l  Consumption  per  Brake   Hnrsi-   I'ower  per  0.57  Ibs. 

Hour     

Oil    Consumption    per    Brake    Horse    Power    per  0.03  Ibs. 

Hour     

Propeller 

Material 

Diameter,  according  to  requirements  of  performance. 

Pitch,  according  to   requirements  of  performance. 

Maximum  Range 
At  economic  speed,  about  875  miles. 


42 


MILTI-MOTOKK1)   .\KKOPI..\\KS 


I       .    I       N 

from   >•'  |    In    lin  .    hours. 
In  iiml'.K-tiire. 


ng  Bout,  equipped    uitli  two   Liberty   inuturs.      It   ca  ••  n.  and   li.is  a   cruising  railins  of 

Throughout,    I  In-    \arious    p.irt     «re   so  designed    that   efficient    priMluction    methods    ean    !«•    used    in    its 


F-5-L  Navy  Flying  Boat 


Tin-  II  I  lying  Moat  is  a  twin-motored  tractor  bi- 
plane, ha  \ing  n  total  Hyinn  weight  nf  lu-arly  7  tons,  a 
cruising  radius  of  ]iil._.  hours  as  a  tighter,  or  S1-  hours 
as  -i  liiiiiilu-r.  It  carries  a  military  load  of  over  I  KM)  Ibs., 
with  -i  crew  of  four  mm.  It  is  so  designed  that  it  may 
l)r  ijiiii-kly  .-Hid  efficiently  built. 

Tin-  I '  ."•  I  is  i  somewhat  larger  machine  than  either 
the  II-l-J  or  the  H-l(i  and  is  capable  of  carrying  a  greater 
useful  load. 

I  Mini  urn  iit.illy  the  plnnc  is  similar  to  our  American 
Curtiss  Hying  bouts  —  particularly  the  H-1G  model.  Hut 
in  si/e  .'11111  details  it  is  quite  different,  being  larger  and 
better  titled  to  emergency  production.  For  example,  with 
\eeptinns  the  fittings  are  soft  sheet  steel,  cut  from 
Hat  patterns  and  bent  to  shape. 

This  obviated  the  necessity  of  dies  and  drop  forcings, 
which  are  particularly  difficult  to  obtain  under  war  condi- 
tions. The  struts,  likewise,  are  uniform  sections,  that  is, 
not  tapered,  so  that  they  can  be  shaped  with  a  minimum 
of  hand  labor.  Throughout,  the  parts  are  such  that  du- 
plication is  easy,  production  methods  possible,  and  read- 
ily available  equipment  suitable. 

The  specifications   herewith   will  give  some  idea  of  the 

si/,     mil  eapaeity  of  this  seaplane.      It   will  be  noted  that 

the  lift  per  square  foot  of  surface  is  from  9.3  to  9.")   Ibs. 

,uare  foot  and  is  somewhat  greater  than  land  prac- 

The  I-' -.1-1.  is  the  latest  development  of  the  boat  type 
seaplane,  having  the  tail  surfaces  carried  on  the  fuselage 
construction  and  the  fuselage  entering  into  the  hull  of 


the  boat.     The  Curtis,  boat  seaplane  may  be  i sidcrcd 

a  forerunner  of  this  type.  The  characteristics  nre  a  fuse- 
lage similar  to  that  of  a  land  machine,  planked  in  to  form 
a  boat  body  and  having  planes  or  steps  similar  to  a  hydro- 
plane at  the  forward  end. 

Sl'l.c  II  If  VI  IciNS  OK   \.\VY  F-5-L  FLYING   IK  i  \  I 

Overall  upper  wing   (including  ailerons)    103  ft.  9%  In. 

Overall    lower   win*    7»  ft.   I   in. 

Overall  li-ii(rtli  of  lin.it    49  ft.  311,,,  in. 

Overall  heijflit  of  boat   1H  ft.  91 4'  in. 

\Vimr  chonl   (II-IJ  curve)    H  ft. 

Cup  iM-twren  upper  and  lower  panels  C.  I..  brams.H  ft.  10%  In. 

Antflr  <>f  incidence  of  wlnjrs  plus   3  drg.  4<)  mln. 

Dihedral  of  winjf   1 '  .   d.  ir 

Stagger  of  win);*   Nnne 

Angle  of  incidence  horizontal  stab,  plus iyt  deg. 

F.ngine  sect,   panel    10H  sq.  ft. 

liili-nn.  and  upper  outer  panels  (31 1  s<).  ft.  each) 611  sq.  ft. 

A il.-nins   (.',!)  sq.  ft.  each)    11H  «q.  ft. 

Sidewalks   (:«  s<|.  ft.  each)    66  sq.  ft. 

Ixiwer  wings  (.'Ml  sq.  ft.  each)    - 

Nun-skid  planes   ( l.i  si|.  ft.  each)    3<l      i     't. 

Horiwmt.il   stahilij^-r    1 2\  -     'ft 

Vertical  stal.iliwr 35  *     ft 

Klevators   (.•*  .sq.  ft.  each)    56  s.      ft. 

Rudder    33»     ft 

Total  lift  surfaces    (including  ailerons)    1.394  s      ft. 

Mull   length    45  ft.  :t 

Hull    width    -ft. 

Hull  height  «  ft.   1        in. 

Pontoon  length  •    ft. 

Pontoon    width     "in. 

Pontoon     height 35%  to. 

Power  plant   .'I  .ilx-rty   Motors 

Pro|M-llers  (subject  to  change),  '-blade. .  .10</,  ft.    fi",  ft.  pitch 


Hear  view  of  the  K-5-1.  flying  boat  in  flight. 


TEXTHOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Streamline  of  Boat  Noteworthy 

The  most  noticeable  feature  in  the  F-.i-L  is  the  degree 
to  which  the  hull  or  boat  has  been  streamlined.  The  hull 
cover  sweeps  aft,  broken  only  by  the  cockpit  openings. 
From  an  aerodynamic  standpoint  this  is  more  efficient  than 
the  construction  of  the  H-16,  where  a  raised  cabin  is  used. 

On  this  model,  as  on  the  H-16,  the  fin  edges  are  con- 
tinued aft  and  join  into  the  lower  longeron,  giving  a 
much  stronger  structure  and  better  streamline  form.  An- 
other feature  in  the  hull  construction  that  is  noteworthy 
is  the  use  of  veneer  instead  of  linen  doped  and  painted  on 
the  after  hull  sides.  It  was  found  in  practice  that  the 
linen  failed  in  heavy  seas  or  on  a  bad  landing,  but  this 
failure  was  obviated  by  the  use  of  veneer. 

With  few  exceptions,  all  large  seaplanes  have  been  pre- 
viously built  with  unbalanced  control  surfaces.  However, 
on  the  F-5-L  both  the  ailerons  and  rudder  are  balanced. 
The  purpose  is,  of  course,  to  increase  the  controllability 
of  the  unit,  and  in  the  case  of  the  aileron  control  the  re- 
sult is  as  anticipated. 

Differing  from  the  usual  control  surface  balance  con- 
struction, the  balance  on  these  ailerons  is  cambered  so 
that  it  has  a  positive  lift.  By  this  construction  the  ailer- 
ons tend  to  be  more  sensitive  in  their  action  and  to  operate 
with  less  difficulty  and  with  less  balance  surface. 

The  planing  action  is  increased  by  the  use  of  vents  ex- 
tending through  the  hull  aft  of  the  rear  steps,  similar  to 
the  vents  that  are  used  on  the  pontoons  of  the  R-6  Cur- 
tiss  model.  It  was  stated  that  the  hull  swept  aft  in  a 
perfect  streamline,  and  the  cabin  top  over  the  pilot's  cock- 
pit was  eliminated.  However,  a  certain  amount  of  pro- 
tection is  afforded  the  pilot  by  small  adjustable  wind- 
shields. 

The  whole  layout  of  the  machine  is  such  that  the  du- 
ties of  the  crew  may  be  most  readily  carried  out.  The 
observer's  cockpit  is  in  the  nose  of  the  machine  and  from 
it  the  widest  range  of  vision  is  possible.  At  the  bow  is 
mounted  the  bomb  sight  and  adjacent  to  it  are  the  bomb 
release  pulls,  ammunition  racks,  signal  pistols,  binoculars, 
etc.  A  machine  gun  turret  is  mounted  on  the  scarf-ring 
of  the  forward  cockpit,  so  that  the  observer  may  aid  in  re- 
pelling aircraft  attacks  or,  if  necessary,  sweep  the  deck 
of  the  submarine  with  machine  gun  fire. 

The  pilot's  cockpit  is  just  aft  the  observer's  cockpit, 
and  may  be  readily  reached  from  it  when  the  machine  is 
in  flight.  The  pilots  are  seated  on  comfortable  seats, 
hinged  on  a  bulkhead  and  attached  to  a  transverse  tube 
by  means  of  a  snap  catch  that  may  be  instantly  released. 
This  permits  the  observer  to  pass  aft  at  will  without  dis- 
turbing the  pilot. 

A  wheel  control  of  the  dual  type  is  used.  It  comprises 
a  laminated  ash  yoke  on  which  are  mounted  the  two  aileron 
wheels  connected  by  an  endless  chain.  An  instrument 
board  containing  tachometers,  altimeters,  air  speed  indi- 
cator, oil  pressure  indicators,  inclinometer,  and  pilot- 
directing  bomb  sight  is  mounted  directly  in  front  of  the 
pilot. 

On  the  starboard  side  of  the  hull  are  the  individual 
engine  switches,  ammeters  and  emergency  switches,  to- 


gether with  the  circuit  breakers.  The  two  compasses  are 
mounted  at  some  distance  apart,  so  that  they  cannot  inter- 
fere with  each  other.  One  is  on  the  deck  and  the  other 
on  the  fioor.  All  instruments  are  self-luminous,  but  in- 
strument hoard  lights  are  provided. 

The  spark  controls  are  at  the  starboard  side  of  the  star- 
board pilot's  seat,  but  the  throttle  controls  are  between 
the  two  pilots,  so  that  either  may  operate  them.  Fire 
extinguishers  are  placed  conveniently  at  each  station, 
those  in  the  pilot's  cockpit  being  attached  to  the  bulk- 
head beneath  the  seat. 

The  wireless  operator's  station  is  on  the  starboard 
side  just  aft  the  pilots.  The  equipment  is  mounted  on  a 
small  veneer  table,  and  used  in  conjunction  with  a  tele- 
scopic mast  that  is  carried  in  the  stern.  A  celluloid  win- 
dow in  the  hull  side  provides  necessary  light. 

Mechanics  Stationed  Amidship 

The  mechanics'  station  is  amidships  by  the  gasoline 
tanks  and  pumps,  and  their  main  duty  is  to  see  that  the 
plane  is  "  trimmed  "  by  pumping  gasoline  from  the  tanks 
alternately ;  to  see  that  the  engines  do  not  overheat,  and 
that  all  parts  function  properly.  The  water  and  oil 
thermometer  are  mounted  on  the  sidewalk  beam  adjacent 
to  the  mechanics'  station. 

Aft  the  mechanics'  station,  or  wing  section,  is  the  rear 
gunner's  cockpit.  Three  guns  are  accessible  from  this 
station,  and  it  also  provides  a  good  point  of  observation 
or  position  for  aerial  photography. 

All  machines  are  equipped  with  inter-communicating, 
telephones,  the  receivers  being  incorporated  in  the  helmets 
and  connection  effected  by  terminal  boxes  at  each  station. 
It  is  thus  possible  for  all  members  of  the  crew  to  be  in 
constant  communication. 

Voluminous  Equipment  Carried 

In  addition  to  the  equipment  indicated,  the  following 
are  some  of  the  miscellaneous  items  usually  carried:  Tool 
kits,  water  buckets,  range  and  running  lights,  pigeons, 
emergency  rations,  drinking  water,  medicine  chest,  sea 
anchor,  chart  board,  mud  anchor,  anchor  rope,  heaving 
lines,  signal  lamp,  binoculars,  Verys  pistol,  ammunition, 
life  jackets,  and  possibly  electric  warmers.  Included 
also  are  the  priming  cans,  drinking  cups  and  usually  sev- 
eral personal  items.  All  this  is  exclusive  of  the  ordnance 
equipment  of  bombs,  machine  guns,  etc. 

Considering  the  size  of  the  machine  and  the  amount  of 
material  carried,  the  performance  is  quite  remarkable. 
In  fact,  it  compares  very  favorably  with  the  performance 
of  land  planes  having  the  same  specifications  and  not 
hampered  by  the  heavy  boat  construction. 

The  time  required  to  get  the  machine  from  the  water 
varies  with  the  wind  velocity,  but  with  a  15-mile  wind 
and  the  plane  fully  loaded,  from  30  to  40  sec.  is  required. 
The  speed  at  take-off  is  about  47  knots  on  the  air  speed 
indicator,  and  a  machine  of  this  design  has  made  a  climb 
of  4200  ft.  in  10  rain. 


28 . 


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Design  of  the  new  four-motored  600  h.p.  passenfter-carrying  Sikorsky  biplane. 


HANDLEY   PAGE 

TWW  LIBERTY  MOTORED 

TYPE O100  BOMBER 


Scale  cy  /«•! 


46 


MULTI-MOTOR KI)   AKRO1M.AXKS 


Tin-  Twin-Libcrty-Motorcd  American  Handley-l'age. 


A  machine  of  tins  typr  can  be  utilized  fur  lung  distance  mail,  passenger  and 
freight  service. 


The  Handley-Page  Type  0-400  Bomber 

Hoth   in  Great  Britain  and   in   the   United  States,  the  General  Dimensions 

H.-m.llev-l'agc   h.-is   heen   the  principal  machine  to  be  put      SP«".  "PP"  Plane    

,         ,         ,  .                                    rp.  Span,  lower  plnne    70  ft.    0  in. 

into    <iu:mtity    production    fur    bouMag    purposes.     The  ( •',„,„,_  ,„,,,,  ],,„„,.„   lofi.   ciin. 

American  design  is  similar  to  the  British,  except  that  Lib-  ^ap  between  |. Lines    1 1  ft.   "in. 

erty  "  I-'"   K)0  h.p.  engines  are  employed  in  the  former.  Length  over  all   63ft.  10  in. 

and  the  Holls-Royce  or  Sunheam  in  the  latter.  Height  over  all  at  overhang  cahane  .                                         0  In. 

A«-" >»i-   •«  «•*   <<»•  one   pilot   and   two  or 

three   gunner*,  and  an  observer  who  operates  the  bomb- 
dropping  devices.     Their  placing  is  ns  follows:     At  the  Areas 
forward  end  of  the  fuselage  is  the  gunner  who  operates  a  Si/nor* 

ii.iir  of  flexible  Lewis  machine  guns.      Bowden  cables  at 

....           ,               ,  ,        ,           T,  I  pper  plane  with  ailerons   lOlH 

one  side  of  the  cockpit  permit  the  release  of  bombs.     Be-  y^WJM  (2)  each  Hi 

lun.l  th<  -gunner  is  the  pilot's  cockpit  from  which  the  gun-  |x)Wer    p|ane    630 

ner's  cockpit  is  reached  through  an  opening  in  the  bulkhead  Total  wing  area  with  ailerons  1648 

separating  the  two  compartments.     The  pilot  is  seated  at       I'pper  stabilizer   

th.  right  side  of  the  cockpit.     Beside  him  is  the  observer's  {^*"to^ah("'j"'r                                                                      ^0 

seat,  hinged  so  it  may  be  raised  so  as  to  permit  access.  j..jn                                                               H  7 

Bomb-releasing  controls  are  placed  on  the  left  side  of  the  Rudders    (3)    46 

observer  extending  to  the  forward  gunner's  compartment 

and  running  back  to  the  bomb  racks  located  in  the  fuselage  Weights,  General                         Pound, 

just  between  the  wings.  Machine  empty   1466* 

Forward   compartments   are   reached   via   a   triangular  FueJ  amj  ()j|   3496 

door  on  the  under  side  of  the  fuselage.  Bomhs    So* 

Aft  of  the  bomb  rack  compartment,  the  rear  gunners  Military  I-oad    . 

are  placed.     Two  guns  are  located  at  the  top  of  the  fusel-  *•£*?£*,£ '  1 1 ; ; '. ;  \  ]  \  \  \  \  \  \  \  ]  \  \  \  \  \  [  \  [  \  \  \  \  \     *»M 

age  and  a  third  is  arranged  to  fire  through  an  opening  in  Weignt  per  horM.  pawn  175 

the  under  side  of  the  fuselage.     One  gunner  may  have 

charge  of  all  the  rear  guns,  although  usually  two  gunners  Summation  of  Weights 

man  them.     A  platform  is  situated  half  way  between  upper  Power  Plant    . . . 

and  lower  longerons  of  the  fuselage,  upon  which  the  gun-  fjjjj^  amj  'n,,^,,,,,^'  ^uip^nt  '^i '.! ! !  i!" !!      610 

ner  stands  when  operating  the  upper  guns.  Armament     3°* 

Machines  of  this  type  can  be  utilized   for  commercial  Bombing  equipment  •••     3000 

aerial  transportation,  and  are  capable  of  carrying  loads  Body  structure  . 

which  would  enable  them  to  efficiently  perform  this  func-  Tall  ""^^^  •  •                                                      '"•'    ^^^ 

tion.     By  leaving  off  the  various  military  fixtures,  the  use-  chj)£u 710 

fill  carrying  capacity,  for  passengers  or  freight,  will  be 

greatly  increased.  Total     


48 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


WEIGHT  SCHEDULE 
Power  Plant 

Engin.e  complete   with  carburetor  and   ignition   system 

J  x  835  =    

Radiator    2  x  112  =    

Hadiators  and  engine  water  -2  x  150  =   

Fuel  tank  empty  and  pipes   

Oil  tank  empty  and  pipes  16x2=  

Exhaust   manifolds   -2  x  7.5  =    

Propeller  and  propeller  hubs  3  \  GO  =    

Cowling   -2  x  100  =    


rounds 

1688 
994 
300 
350 
32 
150 
190 
200 


Volumes 

Bomb  section,  3  ft.  5%  in.  x  5  ft.  2  15/16  in.x4  ft.  5  in. 
Hear    gunner's    platform    (upper)    3    ft.   3'/8    in.  x  5    ft. 

1%  in.  x  4  ft.  -"/,  in 

Hear    gunner's    platform     (lower)     2    ft.    4.    in.  x  5    ft. 
1%  in.  x  4  ft.  ->'/,  in 


Cu.  Ft. 
80.6 

71.45 
54.2 


Total   volume    200.25 


Total 


Height 
(Feet) 
0  . 

5,000   . 

7,000 


Performances 

Speed  Time  of  Climb 

(M.l'.ll.) (Minutes) 

. . .     92      0 

.  . .      90      12 

18 


Fuel  and  Oil  10,000  85     32 

Fuel  (280  gallons)    2280 

Oil  (2x  15.3  gallons  2x  108  ll,s.)    =J18 

Planes   are   not   swept   back   and   have   no   stagger   nor 

Total     -196  decalage.     Beyond   the   engine   nacelles,  both   upper   and 

Passengers  and  Equipment  l°wer  Planes  have  a  dihedral  angle  of  4  degrees. 

Pilot  and  clothing  170  ^'ing  section  employed,  R.  A.  F.  No.  6.      Angle  of  lower 

Gunners  and  clothing   340  wing  chord  to  propeller  axis,  3  degrees. 

Dashboard    instruments,    fire    extinguisher,    tools    and  Aspect  ratio  of  upper  wing,  10;  lower  wing,  7. 

maPs     Planes  are  in  nine  sections.     Upper  plane  center  section 

Total                                                                                     gjO  16  ft.  0  in.  wide.     Intermediate  sections  22  ft.  0  in.  wide; 

overhang  sections   16   ft.    10  in.   wide.     Beyond   this,  the 

Armament  ailerons  project  for  a  distance  of  3  ft.  2  in. 

Two  forward  machine  guns,  mounting  and  ejection  am-  Lower     ,ne  jn  four  sections .  two  between  fuselage  and 

munition   and   sights    12X) 

Three  rear  machine  guns,  mounting  and  ejection  am-  eng'ne  nacelles  and  two  outer  sections. 

munition  and  sights  180  Interplane  struts  spaced  as  follows :  nacelle  struts  8  ft. 

0  in.  from  center  of  body;  intermediate  struts  10  ft.  0  in. 

Total     from  nacelle  struts ;  outer  struts   1 2  ft.  0  in.  from  inter- 
Bombing  Equipment  mediate  struts.     Overhang  rods  anchored  14  ft.  0  in.  from 

Bombs    2500  outer  struts.     Overhang  beyond  bracing  6  ft.  0  in.,  includ- 

Bomb  releases  and  sights  500  jng  ailerons. 

Ailerons  are  20  ft.  7%  in-  5°n£;  3  ft.  9  in.  in  chord. 

i  otal      oOOO 

Overhang  portion  3  ft.  lyj  in.  wide. 

Body  The   accompanying  drawing  illustrates   the   manner   in 

Body   frame   953  +  97  =  whieh  the  main  planes  are  hinged  aft  of  the  engjne  na- 

Front  control' and  rear  control' !!!!!!  i!/!! !'" !!!!"!!       100  celles'  Permitting  the  wings  to  be  folded  back  so  as  to  fa- 

cilitate   housing   in   a   comparatively   narrow   hangar.      In 

Total     1210  folded   position    the   measurement    from   leading   edge    of 

Tail  Surfaces  with  Bracing  wi°?  *»  centerl'ne  of  fuselage  is  15  ft-  6  in- 

,_„  For  bracing  between  planes,  oval  section  steel  rods  are 

Stabilizers  (no  covering)  3 57.2 

Elevators  (no  covering)  4 34.4  used    exclusively.     Jinds    are    formed    to    a    solid    section 

Fin  (no  covering)   1   6.4  which  is  threaded  and  fitted  with  a  trunnion  barrel  and 

Rudder  (no  covering)  2  28.8  forked  terminals. 

Covering     35.4  _       . 

Struts  and  wires ,         24.4 

The  fuselage  is  built  up  with  the  usual  longerons  and 

Total     187.  cross  members.     Bracing  is  with  solid  wires  with  swaged 

Wing  Structure  or  forked  ends' 

Upper  wing  with  fittings,  aileron  and  fuel  tank  in  center  Total    length    of    fuselage,   62    ft.    10%    in.;    maximum 

section;  lower  wing  with  fittings   2032  width  at  tile  wings,  4  ft.  9  in.,  tapering  in  straight  lines  to 

Interplane   struts 235.5  2  ft.  11  in.  wide  at  the  stern ;  maximum  height,  6  ft.  10  in. 

Interplane  cables    ...                                                                261  jn  flving  position  the  top  longerons  are  horizontal  to  the 

Nacelle  supports  2  x  105  =   210  " ,,                           ,                        ,  ,.     „  . 

propeller  axes;  top  longerons  12  ft.  3  in.  above  ground. 

Xotal     2738.5  Leading  edge  of  planes  1 2  ft.  2  in.  aft  of  fuselage  nose. 

Chassis  Tail  Group 

Wheels  complete,  2  x  170  =    340  The  tail  is  of  the  biplane  type  with  a  gap  of  6  ft.  0  in. 

Shock  absorber,  4  Average  chord,  8  ft.  6  17/32  in.     Chord,  above  bodv,  5  ft. 

Miscellaneous  parts,  4  x  30  == 120  °_             ,'                                                                               •  ' 

Tail  skid                                                                                       50  ln'      ^pan  °f  stabilizers,  16  ft.  7y->  in. 

There  are  two  pairs  of  elevators  1  ft.  10  15/32  in.  wide 

Total     710  and  8  ft.  5  JX>  in.  long. 


MII.TI-.MOTOKKI)   AKKOIM..XM-  - 


M 


The  «  iiu;  rim-triirtion  of  tin-    lliiinllc\-l'.ij:e  machine-. 


Struts  fruiii  hotly  to  top  t.-iil  plane  spaced  2  ft.  !»'  t  in. 
from  renter  to  center.  From  these,  tlir  outrr  forward 
struts  and  rudders  are  spaced  i>  ft.  :>'„  in. 

Central  M rtical  tin,   I  ft.  ()  in.  wide. 

Rudders  are  balanced.  Width  t  ft.  HI' -in.  Control 
failles  run  to  their  tr.-iilini;  >  ili:<  >.  and  a  MBpeBMtfag 
cable  runs  through  the  fin  from  the  leading  edge  of  one 
rudder  to  the  Icadiiii:  cdae  of  the  other. 

Landing  Gear 

The  landing  gear  comprises  four  2  ft.  11  7/16  in.  dinm- 
cter  wheels  with  tires  7^  j,,  wide.  Wheels  arranged  in 
tun  |i  i;r-  <  :ieh  pair  h.-iving  a  4  ft.  6  in.  tread,  and  inner 
wheels  spaced  5  ft.  Sfo  in.  from  center  to  center. 

.\\le-,  -in  Imiu"  il  at  center.  Vertical  shock  absorber 
iiiecli.-inisiii  enclosed  in  /in  aluminum  casing. 

Tail  skid  is  the  usual  swivelled  pylon-mounted  ash  skid, 
shod  with  a  sheet  steel  plate. 

Engines 

Tin-  Liberty  engines  are  entirely  enclosed  in  streamlined 
sheet  aluminum  nacelles  between  the  planes.  Propeller 
axes  10  ft.  Ill  16  in.  above  ground  when  machine  is  in 

Hying  position. 


MANDLEY-PAGE 


((Mr     Hi'     till'     four     shock     ;lli 

sorlx-r  units  nf  the  IUmll<-\ 
Pafrr  ItmulH-r.  The  stream- 
line sliet-t  .iliniiimiMi  en-iriu' 
is  rrmoxetl  til  sliow  the  nirth 
IM)  nf  -trin^illj.'  the  rlasti<' 
cnril  tH-twt  ell  v.nlilles  llttlicheil 
tn  tin-  I  i  \i-il  linicr  MI  ii  I  the 
.slidini.'  rinls  res|iecti\fl\. 


Propellers   10  ft.  6  in.  diameter.  Imth   revolving  in  the 
same  direction. 

Kadiator  faces  have  adju.stnhle  shutters  to  regulate  tin- 
air  admittance.      Water  capacity  of  radiators,  ,S(M)  Ibs. 

Each  of  the  two  Liberty  "  1-J  "  engines  gives  -KM)  h.p. 
at  1.625  r  p.m.      More  and  stroke  5x~  inches.      I  in  I  ton 
sumption,  ..95  Ibs.  per  h.p.  hour;  oil,  .03  Ibs.  per  h.p.  hour. 
Engine  weight,  M,  (Ht  Ibs.  with  propeller. 

Tanks  located  above  bomb  compartment.      Fuel  capac- 
ity, 280  gallons;  oil,  15.3  gallons. 


Thr  transatlantic  type.  British  make.  Handle) -Pap-  biplane,  powered  with  four  Rolls-Kojcc  motors 


50 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  J.  V.  Martin  Cruising  Bomber.  One  of  the  very  original  machines  developed  in  this  country  by  Captain  James  V. 
Martin  for  the  U.  S.  Army.  Two  Liberty  "1-3"  engines,  located  within  the  fuselage,  drive  two  four-bladed  tractor  screws 
by  means  of  bevel  gears.  This  machine  has  the  Martin  automatic  wing-end  ailerons,  K-bar  interplane  struts  and  other  un- 
usual mechanical  constructional  features. 

The  Martin  Cruising  Bomber 


The  Martin  Cruising  Bomber  is  equipped  with  two  en- 
gines located  in  the  fuselage  and  driving  two  tractor  pro- 
pellers by  means  of  bevel  gear  transmission.  Since  either 
engine  will  drive  both  propellers,  the  failure  of  one  of 
the  engines  does  not  impair  the  efficiency  of  the  plane. 

Either  two  Sunbeam  300  h.p  will  drive  the  plane  at 
74  m.p.h.,  or  two  Liberty  400  h.p.  engines  will  drive 
plane  at  81  m.p.h.;  in  either  case  with  a  two  ton  useful 
load. 

Fully  loaded  the  machine  can  make  a.speed  of  110  miles 
an  hour.  The  useful  load  is  three  tons  not  including  one 
ton  of  fuel  and  oil. 

The  K-bar  cellule  truss  is  used,  which  eliminates  half 
of  the  cellule  structural  resistance  due  to  wires  transverse 
to  the  line  of  flight. 

The  machine  is  also  provided  with  the  Martin  retract- 
able landing  chassis,  which  has  been  found  to  be  strong, 
light  and  reliable.  It  eliminates  14  per  cent  of  the  struc- 
tural resistance  of  the  Bomber. 

Mr.  Martin  claims  that  safety  and  dependability  are 
increased  because  of  independent  transmission  support, 


for  the  propeller  breakage  will  not  endanger  cellule  truss, 
and  because  cellule  stresses  are  low  and  are  more  ac- 
curately calculable. 

As  the  engines  are  enclosed,  resistance  is  no  greater 
than  where  a  single  engine  is  used.  Such  placing  makes 
the  engines  accessible  for  minor  repairs  and  adjustments. 


View  of  the  power  plant  of  the  J.  V.  Martin  Cruising  Bomber. 


A  view  of  the  Martin  Blue  Bird  in 
flight.  This  small  machine  has  the  K-bar 
truss  and  retractable  landing  gear,  as  does 
the  Martin  Bomber  described  above. 


Mn/n-MOTOHKI)  AKKOl'I.AM.S 


51 


Tin 


Martin  Twin   l.ilx-rtv   Motored    Bomber. 


Glenn   L.   Martin   Bomber 


The  Martin  bomber  is  a  machine  of  excellent  perform- 
ance, as  show  n  in  its  official  trials.  An  official  high  speed 
at  the  ground  of  11H..">  m.p.li.  was  made  on  the  first  trials, 
with  t  ill  bomhiin:  load  on  l>oard.  This  speed  lias  been 
bettered  since,  due  to  the  l>etter  propeller  efficiency  arrived 
at  by  e\pi-nsj\e  experiments.  With  full  bomb  load,  the 
cliinhinir  time  to  III.OIMI  ft.  was  I  ,"i  niin..  and  a  service 
ccilini:  of  between  lii.oiin  and  I7.OIM1  ft.  was  attained. 

As  i  militarv  in.-ieliiiie.  the  Martin  Twin  is  built  to  ful- 
fill tin  rci|uircnicnts  of  the  four  following  classes:  (1) 
night  bomber:  (2)  day  bomber;  (3)  long  distance  photog- 
raphy; (  1)  gun  machine. 

\-  i  night  bomber  it  is  armed  with  three  flexible 
I  •  w  is  machine  guns,  one  mounted  on  the  front  turret,  one 
on  the  re.-ir  turret,  and  the  third  inside  the  body,  and  firing 
to  the  rear,  liclow  and  to  the  sides,  under  the  concave 
lower  surface  of  the  body.  It  carries  l.'.(M)  pounds  of 
bombs  and  looo  rounds  of  ammunition.  A  radio  tele- 
phone s,  t  and  the  necessary  instruments  are  carried  on  all 
four  types.  The  fuel  capacity  in  all  four  types  is  suffi- 
cient for  one-half  hour  full  power  at  the  ground  and  six 
hours'  full  power  at  1 .1,000  feet,  and  enough  more  for 
about  six  hundred  miles. 

As  a  day  bomber  two  more  Lewis  guns  are  carried, 
one   more   on    each    turret.      The    bomb   capacity    is   cut    to 
!bs.    to    give    the    higher    ceiling    necessary    for    day- 
work. 

(3)  When  equipped  as  a  photography  machine,  the 
same  number  of  guns  as  in  the  case  of  the  day  bomber  are 
carried ;  but  in  plaee  of  the  bombs  two  cameras  are 
mounted  in  the  rear  gunner's  cockpit.  One  camera  is  a 
short  focal  length  semi-automatic,  and  the  other  is  a  long 
focal  length  hand-operated  type. 

The  gun  machine  is  equipped  for  the  purpose  of 
breaking  up  enemy  formations.  In  addition  to  the  five 
machine  guns  and  their  ammunition  as  carried  on  the 
photographic  machine,  a  semi-flexible  37  mm.  cannon  is 
mounted  in  the  front  gun  cockpit,  firing  forward,  and  with 
m  fairly  wide  range  in  elevation  and  azimuth.  This  can- 


non fires  either  shell  or  shot,  and  is  a  formidable  weapon. 
The  Martin  Twin  is  easily  adaptable  to  tin-  commercial 
uses  that  are  now  practical.  They  are:  (1)  mail  and 
express  carrying;  (  •„' )  transportation  of  passengers;  (  :( ) 
aerial  map  and  .survey  work. 

(1)  As  a  mail  or  express  machine,  a  ton  may  be  carried 
with  comfort  not  only  because  of  the  ability  of  the  machine 
to  efficiently  handle  the  load,  but  because  generous  bulk 
stowage  room  is  available. 

(2)  Twelve    passengers,    ill   addition   to   the   pilot   and 
mechanic,  can  be  carried  for  non-stop  runs  up  to  six  hun- 
dred miles. 

(S)  The  photographic  machine,  as  developed  for  war 
purposes,  is  at  once  adaptab.<  to  the  aerial  mapping  of 
what  will  become  the  main  flying  routes  throughout  the 

General  Dimensions  and  Data 

1.     Power  Plant 

Two  l.'-cyl.  Liberty  engines. 

i.     Wing  nml  Control  Surface  Areas. 

Main    planes    (total)    1070       sq.  ft 

I'pper  planes  (including  ailerons    450 

I.ower  planes   (including  ailerons )    '>'<> 

Ailerons     (each)     MJ 

No.   of   ailrrnns    * 

Vertical  Fins  (each)    8.8 

No.   of   fins    i 

Stabiliwr     

Hewitor     M  .''' 

Rudders    (each)    16,50 

Vo.   of   rudders    » 

3.     Overall  Dimensions 

Span,   upper   and    lower    71ft.    5  In. 

Chord,  upper  and  lower  1  "  10  " 

Gap      «  "     «  " 

Length  overall    *«  " 

Height  overall    14  "     7  " 

Incidence  of  wings  with  propeller  axis  

Dihedral None 

Sweep    back    None 

Deealage    (wings)    None 

Stabiliser,  setting  with  wing  chord    

adjustable    between    —  ** 

normal   letting   —  9° 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


country.  The  accuracy  that  is  being  obtained  in  aerial 
photography  should  be  of  vast  value  in  surveying  and 
topographical  map  work. 

Wing  Structure 

The  wing  truss  is  conventional  outside  of  each  of  the 
engines.  From  one  engine  through  the  body  to  the  other 
engine,  the  truss  system  is  a  very  rigid  but  light  one  of 
streamlined  steel  tube  tension  and  compression  members. 
These  members  are  arranged  primarily  with  three  objects 
in  view,  that  is:  (1)  Ease  of  removal  of  the  engines. 

(2)  Rigidity   throughout  the  landing  and  power  system. 

(3)  Simplicity  and  hence  low  weight  and  resistance. 
The   wing  spars   are   of   the   conventional    spruce   eye- 
beam    type.      Interplane    wood    struts    are    two-part    and 
hollow,  and  they  are  pin  connected  to  the  wing  fittings. 
The  wing  ribs  are  of  a  novel  type,  developed  through  very 
extensive   experiments   on   all  types.     They   weigh,  each, 
eleven  ounces   and  have  a  minimum   factor  of   safety   of 
eight.     Scrap   spruce  is   employed  in   their   manufacture, 
and  by  the  use  of  a  clever  jig,  speed  and  accuracy  in  their 
assembly  make  it  a  fine  production  job. 

The  wing  fittings  completely  surround  the  beam  in  every 
case,  and  are  designed  from  every  minute  consideration  to 
give  a  factor  of  safety  in  excess  of  six.  Double  flying 
cables  and  single  landing  and  incidence  cables  are  used 
throughout.  No  turnbuckles  are  employed.  A  right  and 
a  left-hand  threaded  eye-bolt  made  into  the  cable  by  the 
conventional  warp  method,  engage  similarly  threaded 
clevises,  pinned  to  the  fitting  ears.  Streamline  wires  are 
interchangeable  with  the  cables  in  this  system. 

Swaged  tie  rods  are  used  throughout  for  the  internal 
wing  bracing.  Pin  joint  connections  tie  the  lower  wings 
to  the  body,  and  are  also  used  at  all  panel  connections. 

A  minimum  factor  of  safety  of  six  is  secured  throughout 
the  wing  truss  for  the  heaviest  loaded  conditions. 

The  body  in  many  respects  is  the  most  interesting  part 
of  the  airplane.  At  the  nose  is  the  cockpit  for  the  front 
gunner,  mounting  at  its  edge  the  scarfed  gun  mount.  The 
front  gunner  has  access  to  a  passageway  through  which  he 
can  go  aft  to  handle  the  rear  lower  gun,  or  sit  beside  the 
pilot  on  a  folding  seat.  The  pilot  is  placed  on  the  right- 
hand  side  of  the  body  and  well  up  so  that  his  range  of 
vision  is  the  best  possible. 

He  is  provided  with  a  wheel  type  control  and  has  a 


splendid  view  of  the  instrument  board.  At  his  right  and 
under  his  seat  is  the  hand  wheel  which  operates  the  adjust- 
able stabilizer.  Behind  the  pilot  are  the  three  main  gaso- 
line tanks. 

The  passageway  and  firing  platform  for  the  rear  lower 
gun  terminates  at  the  rear  wing  beam  station.  Here,  on  a 
special  mount,  is  the  lower  gun,  which  commands  a  large 
field  of  fire  horizontally  to  the  rear,  below,  and  to  both 
sides.  This  gun  is  operated  from  a  prone  position  by 
either  the  front  gunner,  rear  gunner,  or  a  third  man,  if 
four  are  carried. 

The  tunneling  of  the  bottom  of  the  body  to  permit  the 
mounting  of  the  lower  gun  has  introduced  difficulties  in 
trussing  which  have  satisfactorily  been  solved  in  a  simple 
and  light  manner.  The  lower  transverse  strut  and  cross 
of  transverse  bracing  wires  usually  found  at  each  trans- 
verse section  in  the  truss  type  body  are  replaced  by  two 
steel  tubing  struts. 

The  ends  of  these  struts  are  threaded  right  and  left- 
handed,  and  engage  similarly  threaded  forked  ends  which 
pin  to  the  body  fittings.  By  this  means  the  transverse 
sections  are  squared  up. 

In  all  other  features  the  body  is  a  combination  of  two 
standard  types :  the  wire  and  strut  truss,  and  the  veneer 
plated  wood  truss.  Three-ply  birch  or  mahogany  veneer 
is  used  on  the  body  sides,  at  the  nose  and  tail,  and  in  the 
bulkheads  employed  in  the  body.  Swaged  tie  rods  and 
threaded  clevises  are  employed  throughout  for  truss  ten- 
sion members.  The  longerons  aft  of  the  rear  wing  beam 
station  are  hollowed  out  between  fitting  attachment  points, 
the  degree  of  routing  increasing  with  the  progress  to  the 
rear.  A  cheap,  simple  and  effective  steel  plate  longeron 
fitting  is  employed  at  the  rear  body  panel  points,  while 
heat-treated  chrome  vanadium  fittings  are  found  at  the 
main  wing  truss  attachment  points. 

The  tail  skid  is  braced  entirely  by  the  internal  body 
structure  at  this  point.  It  is  universally  pivoted  and  is 
sprung  by  sturdy  elastic  chords  inside  the  body  to  receive 
the  landing  shock. 

Engine  Units 

The  Liberty  engine  is  firmly  mounted  in  a  light  girder 
box  of  veneer,  resting  on  brackets  on  the  four  main  wing 
struts.  It  is  so  secured  that  engine,  radiator,  airscrew 
and  nacelle  may  be  removed  intact  from  the  wing  struc- 


1  —  One  of  the  four  landing  wheels  showing  the  streamline  shock  absorber  casing  and  the  wheel  guard  to  protect  the 
propeller  from  stones  and  mud.  -2  —  One  of  the  main  ribs,  showing  sections  through  wing  beam  and  leading  edge.  3  —  Fit- 
ting at  ends  of  wing  struts.  4  —  Tail  skid  unit,  with  shock-absorber  elastic  removed. 


MlLTI-MOTOHKl)   .\KHO1M..\N  I  - 


turr.  A  nose  radiator  nf  tubular  i-i-ll  construction,  weigh- 
ing Complete  ^  ll>-..  is  mounted  in  a  unii|uc  and  \rr\ 
satisfactory  iiiainn  r.  Two  ll.iiii;.  .1  steel  rinys  are  In  Id 
together  h\  machine  screws,  .mil  when  in  plan-  wedge  a 
strip  of  rnlilx-r  firmly  between  (lu-in  and  tin  laces  .if  the 
rirculiir  Imlr  cut  in  tin-  radiator  tor  tin  airscrew  shaft. 
Thr  rear  ring  carries  platrs.  which  in  turn  liolt  to  plate-, 
secured  .-it  the  cnil  of  the  engine  hearers.  The  whole 
weight  of  tin-  radiator  then  is  carried  from  its  central 
hole.  \o  |nrt  of  the-  nd:.itor  touches  am  part  of  the 
mounting  hut  has  a  cushion  of  rul>l>er  si paratmg  it  from 
the  mounting  and  absorbing  the-  shock  Iroiu  the  engine. 
I  ich  radiator  is  ei|iiippeil  with  shutters,  operated  nt  tin- 
will  of  the  pilot,  for  the  purpose  of  regulating  the  water 
temperature.  An  expansion  tank  is  let  in  to  the  trading 
portion  of  the  upper  wing  above  each  radiator,  and  is 
connected  to  it.  The  top  of  (he  engine  is  .\poscd.  This 
aids  iii  cooling,  of  course;  makes  the  engine  more  acces- 
sible for  working  o\i  r.  and  permits  the  n  diictioii  of  cowl- 
ing weight  to  minimum  consistent  with  low  head  resistance. 

The  airscrew  used  is  the  Douglas  type,  and  is  9  ft.  8  in. 
diameter  and  li  ft.  1  ill.  face  pitch.  It  is  the  best  over- 
all hlade  git  ing  a  satisfactory  high  speed  and  climb  at 
reasonable  rev  olutions. 

The  three  controls  from  each  engine,  carburetor,  igni- 
tion and  altitude  arc  positive  controls,  operated  easily  and 
convcnicnth  bv  the  pilot,  either  in  pairs  or  singly. 

An  ample  supply  of  oil  is  carried  in  a  tank  situated  in 
each  motor  nacelle. 

Undercarriage 

The  undercarriage  is  composed  of  four  800  by  ISO  mm. 
wheels.  Four  sets  of  triangulated  struts  carry  the  load 
from  the  two  axles  to  the  four  main  structural  points  of 
the  machine.  The  axles  are  hung  on  the  usual  rubber 
cord  suspension,  but  have  a  large  amount  of  freedom  not 
only  vertically,  but  in  the  other  two  directions.  All  the 
lateral  forces  are  taken  up  at  the  center  trussing  under  the 
body.  The  two  outside  sets  of  struts  are  free  to  swing 
laterally,  and  hence  only  absorb  the  vertical  component 
of  the  landing  shock.  Simplicity  with  extreme  low  weight 
and  head  resistance  has  in  this  manner  I  ecu  secured  but 
at  no  expense  to  the  proper  functioning  and  wear  and  tear 
n  sistance  of  the  gear.  The  flexibility  of  this  arrangement 
absorbs  all  kinds  of  shocks  in  a  very  satisfactory  manner. 

Controls  and  Control  Surfaces 

A  single  wheel  and  foot -bar  control  is  provided  in  the 
pilot's  cockpit.  The  interesting  point  about  the  wheel 
control  is  that  the  usual  weaknesses  of  this  tyj)e  have  been 
eliminated.  The  aileron  rabies  pass  over  no  drums,  nor 
they  hidden  within  tubes  where  wear  can  be  detected. 
The  dangers  of  the  chain  and  sprocket  aileron  control, 
with  its  e\er  present  tendency  to  jam,  are  not  encountered 
in  this  type. 

The  IS  in.  wheel  is  keyed  to  a  steel  shaft  which  carries 
on  it,  within  the  upper  gear  case,  an  alloy  steel  bevel  gear. 
This  meshes  with  another  gear  keyed  to  a  vertical  torque 
tulic.  running  in  ball-bearings  mounted  inside  the  control 
column.  At  the  lower  end,  the  tori|iie  shaft  carries  a 
pinion  which  engages  with  a  steel  rack.  The  rack  i« 
guided  inside  the  lower  gear  case,  and  has  attached  to  it 


the  dual  aileron  control  cal  h  s.  The  whole  unit  is  v.rv 
strong,  rigid  ami  reasonably  light.  1'ropcr  power  on  tin- 
lateral  controls  is  readily  obtained,  which  in  the  (Base  of 
either  of  the  other  types  would  m\ol\e  ditiiciiltu  s. 

e.|iial  ami  unbalanced  nilerons  are  carried.  These 
supplv  the  ncci  ss-inh  ln-li  .1.  -n  .  .>f  lateral  controllability 
required  of  ,-i  machine  of  this  t  v  pi 

The  tail  siirfans  ,r.  of  steel  and  wood  const  ruction. 
It  is  noteworthy  that  the  stabili/.er  is  adjustable  from  the 
I'll  I  hi  ,  niir.  tail  surface  structure  is  hinged  at 

the  rear  stabilizer  spar.  The  front  truss  system  termi- 
nates in  a  \ertical  tube,  mounted  in  hi  arings  inside  tin- 
body  and  threaded  to  engage  a  nut.  Tables  wound  on  a 
drum  operated  by  the  hand  wheel  at  the  pilot's  side  turn 
the  nut  and  thus  raise  or  lower  the  front  of  the  stabiliser, 
and  with  it  the  tail  surface  trussing.  A  range  in  angle  .>! 
the  stabilizer  of  plus  or  minus  three  degrees  from  neutral 
gives  the  pilot  n  powerful  means  of  halnncing  the  airplane 
in  any  flying  attitude  or  for  any  load  distribution. 

The   ihvatiir   is   one   piece,   and,   with    its   generous   area 
•  and  ease  of  operation,  forms  a  positive  control  to  be  relied 
on  in  any  emergency. 

Two  balanced  rudders,  working  in  synchronism,  permit 
the  pilot  to  control  his  direction  under  any  conditions  with 
ease.  In  fact,  when  flying  with  one  engine  dead,  the 
amount  of  rudder  movement  necessary  to  correct  the  off- 
setting force  of  the  other  engine  is  surprisingly  small.  It 
leaves  an  ample  margin  of  control  for  maii.eim  ring  under 
these  conditions. 

Gasoline  System 

The  gasoline  system  has  been  developed  to  eliminate 
the  many  troubles  usually  encountered  from  this  vital  part 
of  the  airplane.  Three  sturdy  tanks,  mounted  securely 
inside  the  body,  contain  the  main  supply  of  gasoline.  Two 
gravity  tanks,  mounted  in  the  upper  wing  one  over  each 
engine,  each  hold  gasoline  enough  for  one-half  hour's 
flight.  All  tanks  are  made  from  tinned  steel.  They  are 
braced  securely  by  many  internal  bulkheads,  all  scams  are 
double  lap.  rolled  and  sweated,  and  all  rivets  used  arc 
large  headed  tinned  rop|>cr  rivets.  None  of  the  tanks  are 
subjected  to  any  pressure  when  the  system  is  in  operation. 

The  three  main  gasoline  tanks  drain  into  a  combination 
distributing  valve  and  sump  operated  from  the  pilot's  com- 
partment. Any  tank  can  be  rut  in  or  out  of  the  line  at 
will. 

I'ipes  from  the  sump  lead  the  gas  to  the  two  air-driven 
gear  pumps  located  In-low  the  body.  Valves,  controlled 
by  the  pilot  from  his  seat,  arc  provided  in  the  pump  lines. 
Hy  means  of  these  valves  either  pump  may  be  by-passed 
on  itself  or  allowed  to  feed  gasoline  to  the  carburetors. 
One  pump  alone  is  more  than  sufficient  to  feed  both  motors 
full  on.  Two  are  provided  as  a  safety  means. 

Leads  from  the  pumps  run  out  to  the  carburetors  of 
both  engines.  A  lead  running  from  each  of  these  main 
supply  lines  to  the  gravity  tanks  supplies  them  with  gaso- 
line and  serves  to  carry  off  the  excess  gasoline  pumped  by 
the  main  pump.  An  overflow  pipi  is  led  from  each  gravitv 
tank  to  the  main  tanks. 

A  hand  operated  plunger  pump  is  installed,  and  may 
be  used  to  fill  the  gravity  tanks  or  to  supply  the  engines 
should  I  oth  air-driven  pumps  fail. 


IO 


5UNDSTEDT-HANNEVIO 

TWIN   MOTOBtD 

SEAPLANE 


54 


MII/n-MOTOKKI)   AKKOPLANKS 


The  Sumlste.lt-H.mniM..-  Seaplane  equipped    with  two  Moilrl  "I    I"   1 1  ,II-S.  ,.tt   Kn|(inev 
(lluilt   l>\    tin-   \\itteiii.iim   I.rwis  Airri  -.<-.) 

The  Sundstedt-Hannevig  Seaplane 


Tin-  Stffidatodt-Hannevig  seaplane  lias  In  en  d, signed  for 
tin  specific  purpose  of  long  distance  tlvinir  over  the  sea. 
In  genrrnl.  it  lias  been  designed  with  an  extra  heavy  sub- 
stantial eiinstriietinn.  partieularlv  on  those  parts  subjected 
to  tin-  iircatcst  amount  of  strain  during  flight  and  at  land- 
ings. Midi  as  pontoon-..  HJII^S.  and  the  entire  rigging. 

In  tin  desiiiti.  liowi-vi-r.  only  proved  aerodynamienl  prin- 
ciples have  been  embodied,  assuring  a  positively  efficient 
maeliine.  and  ("apt.  Sundstedt  lias  made  a  large  number  of 
inipro\enients  in  structural  details,  affording  the  utmost 
.strength  anil  lightness  of  construetion. 

Tin  seaplane  is  equipped  for  two  pilots  and  two  pas- 
's in  the  cabin  of  the  fuselage. 


General  Dimensions 


0  in. 
6  in. 
0  in. 
0  in. 

.'  in. 

6  in. 

7  in. 


plane  ...............................  100  ft. 

nwer  plane  ................................    71    ft. 

Imril.  lower  pl.nie   .........................      8  ft. 

•  luinl,  upper  plane   ........................     8  ft. 

'"•tween   w  iiip.    .............................     8  ft. 

'i  nf  i.nieliine  over  all   ......................   50  ft. 

Height   of  in  n  dine  'over  all    ......................    17   ft. 

Dilinlr.il   nnirle.  lower  plane    ..............................  2* 

urvc    ..................................  f.  S.  A.   No.  5 

•n'timr   surfHee    .............................  1,537  sq.  ft. 

Ku.lil.-r    area    .......................................  «  sq.  ft. 

T    area    ......................................  44  sq.  ft. 

\\YitrM      ...........................................  10,000  Ihs. 

I  n.iili'iir  |HT  h.p  .......................................  33  Ihs. 

l.iwilinir  per  sq.  ft  ......................................  6  Ibs. 

estimated,  full  load    ..........................  80  m.p.h. 

('liinliiiifr  s|>citl,  estimated    .................  3,000  ft.  in  10  min. 

total    ........................................  +40 


Pontoons 

Tin  pontoons  are  of  special  Sundstedt  design,  embody- 
ing the  highest  developed  features  of  streamline  and  fol- 
low tin  most  accepted  construction  practice.  They  are 
in  pi'  of  Capt.  A.  P.  Lundin's  special  three-ply  Balsa 
wood  veneer,  covered  with  linen,  and  are  each  divided  into 
eight  watertight  compartments,  painted  and  varnished 


with  torpedo  gray  enamel.  They  are  32  ft.  0  in.  long, 
spaced  16  ft.  ()  in.  apart  from  centers,  and  are  light  in 
weight,  being  400  pounds  apiece,  including  fittings. 

Each  pontoon  is  equipped  with  an  emergeiiey  food  locker 
accessible  from  the  deck  by  means  of  a  handhole. 

The  pontoons  are  braced  to  the  fuselage  and  wings  by 
a  series  of  steel  tubing  struts  with  Halsa  wood  streamline 
fairing.  These  tubes  are  of  large  diameter  and  tit  into 
sockets  mounted  on  the  pontoons  and  wing  spars.  The 
entire  assembly  is  amply  braced  by  steel  cables  and  tub- 
ing connecting  struts. 

Fuselage 

The  fuselage  is  of  streamline  design,  and  is  flat  .siiled 
in  order  to  provide  sufficient  vertical  surface  necessary  for 
good  directional  stability.  It  has  a  curved  streamline 
bottom  and  hood  running  fore  and  aft.  The  construction 
is  of  white  ash  and  spruce,  consisting  of  four  longerons 
and  ash  and  spruce  compression  struts  fastened  thereto 
with  light  universal  steel  fittings,  to  which  are  also  fast- 
ened and  connected  diagonally  the  solid  steel  brace  wires 
and  turnbuckles. 

The  front  end  of  the  fuselage  is  fitted  up  much  after 
the  style  of  a  closed  motor  car,  with  comfortable  up- 
holstered seats  for  the  pilots  and  passengers.  This  cabin 
is  accessible  by  a  door  on  each  side  at  the  rear  end  of  the 
cabin.  A  very  complete  field  of  vision  is  obtained  through 
a  series  of  glass  windows  around  the  front  of  the  pilots' 
seats,  forming  a  recess  in  the  upper  deck  forward  of  the 
windows. 

Directly  behind  this  cabin,  and  balancing  with  the  cen- 
ter of  pressure  is  the  main  gasoline  tank,  with  a  capacity 
of  750  gallons,  sufficient  for  22  hours  of  full  speed  flying, 
and  to  the  rearward  of  this  is  the  adjustable  open  truss- 
ing, with  a  detachable  hood  and  covering  for  access  and 
inspection. 

The  forward  section  is  covered  with  a  thin  three-ply 
mahogany  veneer  up  to  the  rear  of  the  cabin  doors,  and 


56 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Sundstedt  Aerial  Cruiser  being  assembled.     It  is  equipped  with  two  Hall-Scott  motors. 


aft  of  these,  it  is  covered  with  linen,  doped,  painted  and 
varnished. 

Control 

The  control  system  operates  on  the  standard  wheel  and 
rudder  bar  method,  and  is  of  special  Sundstedt  design, 
whereby  all  cables  are  located  beneath  the  floor,  leaving  a 
clean  control  column  and  rudder  bar  without  any  wires 
in  the  way  of  the  passengers  or  pilots.  Dual  control  is 
fitted,  side  by  side,  directly  connected,  so  that  the  ma- 
chine can  be  controlled  by  either  pilot  at  will. 

All  engine  controls  and  switches  are  located  on  the 
dashboard,  operative  from  both  seats. 

Instruments 

A  substantial  dashboard  is  fitted  in  front  of  the  pilots' 
seats  in  a  plainly  visible  position,  and  is  equipped  with 
tachometers  for  both  motors,  clock,  altimeter,  speedometer, 
radiator  thermometers,  oil  pressure  gauges,  shut  off  valves, 
ignition  switches,  and  so  forth,  which  are  located  within 
easy  reach  of  the  pilot. 

Power  Equipment 

The  power  plant  consists  of  two  Hall-Scott  Model 
"  L-6  "  h.p.  engines,  directly  connected  to  two  bladed 
pusher  propellers.  Each  is  mounted  on  a  specially  con- 
structed bed  by  the  Vee  method  of  interplane  struts,  with 
the  engine  beds,  housings,  and  radiators  all  securely  braced 
to  the  wings,  pontoons  and  fuselage. 

The  engines  are  supplied  with  gasoline  by  turbine  driven 
Miller  gasoline  pumps  which  maintain  a  pressure  of  3 
Ibs.  in  a  special  reservoir  of  the  pump  itself,  under  auto- 
matic adjustment,  and  eliminating  all  of  the  difficulties 
and  dangers  of  the  gravity  and  pressure  feed  systems. 
These  pumps  are  regulated  from  the  cabin  and  within  easy 
reach  of  the  pilots. 

Wings 

The  wings  are  built  up  of  five  sections  in  the  top  plane 
and  three  in  the  lower.  The  center  section  of  both  the 


upper  and  lower  planes  are  18  ft.  10  in.  long,  and  so  de- 
signed that  the  pontoons,  the  power  plant,  and  the  fuse- 
lage can  all  be  assembled  completely  before  adding  the 
remaining  outer  wing  sections,  thereby  taking  up  a  mini- 
mum amount  of  space  in  assembly  during  manufacture. 

The  main  spars  are  of  laminated  built  up  section,  serv- 
ing to  give  a  very  high  strength  and  exceptionally  light 
construction  of  a  combined  I-beam  and  a  box  beam  section. 

The  upper  wing  has  a  chord  of  10  ft.  0  in.  at  near 
the  junction  to  the  center  section,  and  narrows  down  to 
8  ft.  6  in.  at  the  inside  of  the  aileron  cutout.  Of  this,  8 
ft.  0  in.  is  well  constructed  web  form  of  rib,  while  beyond 
this  distance  the  cap-strips  are  run  out  with  a  small  piece 
of  spruce  between,  serving  as  a  very  flexible  trailing  edge, 
greatly  increasing  the  stability  and  gliding  efficiency  of 
the  machine. 


The  underside  of  fuselage  showing  control  connections  on 
the  Sundstedt-Hannevig  Seaplane.  It  is  covered  by  an  alumi- 
num cowling. 


MII.TI   MOTOKKI)  .\KltoiM..\\KS 


other  strains  on  the  wings,  and  subjecting  the  wing  ribs 
to  the  one  purpose  of  lift  only. 

The  wing  seetion  used  in  the  I'.  S.  A.  No.  .'>,  whieli  is 
especially  designed  for  |,JK|,  SJM.,.,I  nmj  Kn.at  |if,  Sl.rvjng 
as  a  medium  between  a  scout  and  an  extra  heavy  lifting 
wing,  and,  as  well,  lias  high  structural  safety  factors. 

The  iiiterplane  struts  are  nil  made  of  seamless  steel 
round  tubing,  streamlined  with  Halsa  wood  encased  in 
linen,  and  the  struts  with  reinforced  ends  are  fitted  into 
sockets  which  are  bolted  to  the  main  spars  of  the  wings 
l>y  tour  nicklc  steel  bolts  straddling  the  wing  spar  to  tie 
plates  on  the  opposite  side  of  the  spar. 


The  lower  plain-  is  entirely  constructed  of  solid  rilis. 
with  a  chord  of  S  ft.  ()  in.  The  wing  ribs  are  cut  out  of 
a  spe.-ial  thro  ply  x. n< •,  r.  with  lipped  end-.,  ti t ting  closely 
into  the  boxes  of  the  I-beams,  and  fastened  in  place  bv 
means  of  two  cap  straps,  glued,  nailed  and  screwed  to 
the  webs  and  wing  spars. 

At  the  points  of  fastening  the  iiiterplane  struts  to  the 
main  spars  of  the  wind's,  there  is  an  internal  steel  com 
pression  tube,  reinforced  at  the  ends,  bolted  in  place,  and 
.socket,  fastened  directly  to  the  main  spars,  mtcrhraccd 
diagonally  with  solid  steel  wires  fitted  with  turnbuckles 
for  adjustment  and  locked,  taking  up  all  of  the  drift  and 


**  i  | 


Thr   Kennedy   "  Ciant  "     Xeroplnne,  equipped   with    I   S.ilmsmi  eriirfiies   of  .W  h.p.  each.     Span.   U.'   ft.:   length,  HO   ft.;   height, 
in.;  chord.   II)  ft.;  gap.   IO  ft.;  total   weight,   Ifl.lKK)  ll.s.  empty.     Ttiis  mnrhinr  was  ahamlonrcl  in    1!U7,  hut   th«-   results  „!,- 


•iniil   with   it    h-ne   l.e.-n   put   t,i   use   i,,   huilding  n  not  her  Inrirr  machine.     This   Inttrr  nrroplnnc   has   a  span  of   100   ft.;   length,  44 
hei-ht.  .'.•  ft  ;  estimated  speed.  130-130  m.p.h.;  estimated  useful  load.  6400  Ib*.  in  additinn   to  erew  and  fuel  necessary   for 
i  .VHP  inHe  flight. 


\l 


BURGESS 

TWIN  -  MOTORED 

SEAPLANE 


SCALL    of    FEtT 


McUughlin 


58 


Mri/n-MOTOKKI)   AKHOIM.ANKS 


Burgess  Twin-Motored  Hydroaeroplane 


Tliis  machine,  besides  being  equipped  with  tin-  usual 
complement  of  instruments,  has  the  Sperrv  gvroscopic 
stabilizer  anil  other  impro\cd  installations. 

General  Dimensions 

Span,  upper  plain-   7 .'   f  t.     0  in. 

Span,  lower  plane  51    ft.     !l   in. 

Chord,  Ixith  planes 7   ft.      7    in. 

Cap   iM-tween   planes    6   ft.   11   in. 

Ix-nplli  over  all   :<-'  ft.     5  in. 

II,  ..-hi   over   all    IS   ft.     *  in. 

Cross  writ-lit   5,380  II. s. 

Motors  (.')  Sturdevant  5A,  rnch 140  h.p. 

( Hiding  anple   81/,  to  1 

Climl>  in   in  minutes    3^00  feet 

Spenl   Miiirc,  loaded   78-45  m.p.h. 

Planes 

I'pper  pl.-ine  is  in  .',  sections  —  the  flat  center  section 
12  ft.  (i  in.  wide;  the  outer  sections  each  Hi  ft.  8  in.  wide; 
and  the  overhanging  sections  1 1  ft.  -I-  in.  wide.  The  ends 
of  the  ailerons  project  beyond  the  wing  tips  at  either 
side  for  a  distance  of  1  ft.  6  in. 

Ailerons  on  the  upper  plane  arc  12  ft.  10  in.  in  length, 
minimum  with  2  ft.  1  in.,  maximum  width  3  ft.  5  in.  A 
small  balancing  portion  beyond  the  wiring  tips  extends 
forward  of  the  rear  main  wing  beam.  Control  arms  are 
located  7  ft.  0  in.  from  the  inner  end  of  aileron. 

With  the  exception  of  the  center  sections,  the  planes  are 
swept  back  at  an  angle  of  3  degrees.  On  the  lower  plane, 
this  angle  corresponds  to  a  distance  of  10%  in.  that  the 
straight  portion  of  the  leading  edge  recedes  from  a 
straight  line  at  right  angles  to  the  fuselage  center. 

Dihedral  angle,  center  section,  upper  plane,  180  degrees. 
Dihedral  angle  of  other  wing  sections  178  degrees. 

I'pper  and  lower  planes  are  set  at  a  3-degree  incidence 
angle,  equal  to  rise  in  the  leading  edges  of  4  13/16  in. 
The  transverse  and  lateral  center  of  gravity  is  located 
2  ft.  11  in.  from  the  leading  edge,  at  which  point  a  hoist- 
ing eye  is  located. 

Centers  of  wing  beams  are  located  as  follows:  Front 
beam  i'1  (  in.  from  leading  edge;  beams  4  ft.  6  in.  apart; 
trailing  edge  2  ft.  .S"s  in.  from  center  of  rear  beam.  Wing 
chord,  7  ft.  7%  in. 

Fuselage 

The  fuselage  is  27  ft.  6\'->  in.  long;  maximum  width,  2 
ft.  I-  in.  Maximum  depth  between  longerons,  2  ft.  11  in. 
The  nose  extends  6  ft.  11  in.  forward  of  the  main  planes. 
The  observer's  cockpit  is  located  at  the  nose,  and  the 


pilot    is   located   immediately  below   the  trailing  edge  of 
the  up|>cr  plane. 

Location  of  vertical  fuselage  members  are  indicated  by 
dotted  lines  on  the  drawing.  The  fuselage  termination 
is  IK  in.  high,  formed  by  a  strut  which  carries  the  central 
rudder  and  also  supports  the  tail  float 

Tail  Group 

llori/.ontal  stabilizer,  16  ft.  0  in.  across  at  the  trailing 
edge.  Width.  I  ft.  " ._.  in.  The  leading  edge  is  Straight 
for  a  distance  of  13  ft.  I  in.,  then  curved  in  a  9  in.  radius 
to  a  raked  angle.  It  is  non-lifting.  Klcvators  are  16  ft. 
8%  in.  from  tip  to  tip.  Maximum  width,  3  ft.  8  in. 
Control  posts  located  6  ft.  0  in.  apart,  one  on  each  flap. 

The  vertical  fin  is  3  ft.  2  in.  high,  and  to  it  the  central 
unbalanced  rudder  is  hinged.  The  central  rudder  is  2  ft. 
3  in.  wide. 

In  addition  to  the  central  rudder,  there  are  a  pair  of 
balanced  rudders  located  6  ft.  0  in.  to  either  side  of  the 
rin.  These  rudders  have  a  maximum  height  of  3  ft.  2  in. 
and  a  width  of  2  ft.  2  in. 

Float* 

Floats  are  arranged  catamaran  style,  with  centers  10  ft. 
0  in.  apart.  Each  float  3  ft.  0  in.  wide,  19  ft.  1  Vj  in. 
long  and  2  ft.  0  in.  in  overall  depth.  A  step  3%  in.  deep 
is  located  11  ft.  lO'/..  in.  from  the  front  end.  Struts  to 
the  fuselage  are  located  at  the  following  distances  from 
the  nose:  4  ft.  S  in.;  4  ft.  9  in.;  5  ft.  0  in.  The  dotted 
and  dashed  line  indicates  the  water  line  with  the  machine 
fully  loaded  with  a  weight  of  5380  Ibs. 

The  tail  float  is  19  in.  wide,  4  ft  8  in.  long  and  11%  in. 
deep. 

Motor  Group 

Motor  carrying  struts  are  located  1 1  ft.  7%  in.  apart. 
The  drawing  shows  the  motors  covered  in  with  metal 
cowling.  Propellers  are  8  ft.  10  in.  in  diameter,  rotating 
in  opposite  directions. 

The  motors  are  Sturtevant  model  5 A,  rated  at  150  h.p. 
These  motors  are  8-cylinder,  4-stroke  cycle,  water  cooled, 
with  a  4-inch  bore  and  .">'•.  inch  stroke.  The  normal 
operating  speed  of  the  crankshaft  is  2000  r.p.m.,  and  the 
propeller  shaft  is  driven  through  reducing  gears.  The 
weight  per  h.p.  of  the  motor  is  3.4  Ibs. 

Fuel  is  consumed  at  the  rate  of  26  gallons  per  hour, 
and  tanks  have  a  capacity  sufficient  for  an  eight-hour 
flight 


^••^H 
The  Vickers  "Vimv-1! 


type,  biplane,  equipped  with  two  Holls-Hoycc  303  h.p.  motors 


The  Transatlantic  Type  Vickers  "  Vimy  " 

This  type  of  plane  was  made  famous  by  the  historic  flight  of  Captain  Alcock  and  Lieut.  Bronton 


The  wing  span  of  the  Vickers- Vimy  Biplane  is  67'  2"  ' 
and  the  chord  10'-6",  both  wings,  upper  and  lower,  being 
identical  in  dimensions.  The  area  of  the  upper  wing  is 
686  square  feet,  that  of  the  lower  614,  giving  a  total 
wing  surface  of  1330  square  feet.  The  angle  of  incidence 
of  both  upper  and  lower  wing  is  S^b",  whereas  the 


dihedral  is  3°.  The  surface  of  the  ailerons  is  2-1  '2  square 
feet.  The  areas  in  square  feet  of  the  control  surfaces 
are  as  follows:  tail  plane,  11-1.5;  elevators,  63;  fins,  17; 
rudder,  21.5. 

The  Vickers-Vimy  is  powered  either  by  two  350  horse- 
power Rolls-Royce  Eagle  engines  or  2  Salmon  engines. 
It  was  one  of  the  former  type  which  made  the  successful 
trans-Atlantic  flight.  With  the  Rolls-Royce  its  weight 
empty,  is  6,700  pounds;  loaded,  12,500  pounds,  witli  a 
fuel  capacity  sufficient  for  8.5  hours,  or  a  distance  of  835 
miles. 

The  speed  is  98  miles  an  hour,  and  an  altitude  of  5,000 
feet  is  gained  in  15  minutes.  The  ceiling  is  10,500  feet, 
with  a  military  load  of  2.870  pounds.  The  weight  per 
square  foot  is  9.4  pounds,  and  weight  per  horsepower 
17.9  pounds. 


The  transatlantic  type  Vickers  "  Viniy-Rolls  "  biplane 
CO 


Mil  /ri  -M(  )T(  )1{  Kl )   A  KK<  >1M .  A  N  KS 


Til.-   l.ouplii-.-til   liiphmr,  i-.|iii|.|ii-il   with  two  Hnll-S-ott    A-...I   motor*. 


h'ronl    virw  of   Louche  nl   twiii-niotorril   tlyinjr  hunt    with  two   Ilnll-Siotl    A -.'HI  motor*. 


Tl»    1. ral.am.    \\hite  "Bantam,"  with  its  span  of  JO  feet,  nrxt  to   a   20  pnswngrr  Grahamc- White  twin-motored   l.iplnnr    havinjr  • 

span  of  H9  fcrt. 


62 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


A  group  of  twin-motored  A.  V.  Roe  bombing  planes.     The  machine  on  the  extreme  left  is  equipped  with  two  Sunbeam  aero  en- 
gines, in  the  centre  two  Green  engines,  and  on  the  right  two  Rolls-Royce  engines. 

The  Avro  Twin  Engined  Bomber 


Fitted  with  the  230  h.p.  Galloway  B.H.P.  Motors,  this 
machine  has  the  following  performance  when  fully  loaded 
with  bombs,  etc. 


Ileic/Jit 

'o 

5,000 
10,000 
15,000 
17,000 


Climbing  Trial. 
Time 


min. 


19  </2 


57 


Military  Load 
Rate  of  Climb 

800  ft./min. 

535    "      " 

340    "      " 

170    "      " 

106    "      " 


R.I'M. 
1,420 
1,420 
1,395 
1,355 
1,335 


Height 
0 

5,000 
10,000 
13,000 
15,000 


Speed  Trials 

Spted 
110  M.P.H. 
108  M.P.H. 
106  M.P.H. 
100  M.P.H. 
93  M.P.H. 


R.P.M. 

1,550 
1,540 
1,495 
1,450 
1,410 


This  machine  was  designed  as  a  long  distance  high 
speed  bomber.  It  is  a  3  seater  twin  engined  tractor  bi- 
plane. The  power  units,  which  are  entirely  independent, 
are  mounted  on  the  wings.  One  gunner  is  seated  in  the 
extreme  nose  of  the  body  and  is  provided  with  a  gun 
mounted  on  a  rotatable  mounting.  Fitted  in  the  front 
cockpit  are  the  bomb  sight  and  bomb  release  gear.  A 
second  gunner  is  seated  well  to  the  rear  of  the  main 
planes,  where  he  has  an  exceptionally  good  field  of  fire  in 
every  direction.  He  is  provided  with  complete  dual  con- 
trol for  the  machine  and  two  guns,  one  mounted  on  a  ro- 
tatable mounting  on  the  edge  of  the  cockpit,  and  the  second 
gun  firing  through  the  hole  in  the  bottom  of  the  body  for 
repelling  attacking  machines  coming  up  under  the  tail. 
The  pilot  is  seated  just  in  front  of  the  leading  edges  of 
the  planes  in  an  extremely  comfortable  cockpit. 

Wings 
Dimensions 

Span  of  top  wing    65  ft.  0  in.  The  wings  are.straight  in  plan  form,  with  rounded  wing 

Span  of  bottom  wing  65  ft.  0  in.  j.jpS  an(]  are  made  to  fold,  outside  the  engine  units,  thus 

Chord  of  top  wing   .                                                         7  ft.  6  in.  saving    considerable    shed    room.     The    wing    bracing    is 

Chord  of  bottom  wing                                                                        m.  d      f  tubular     fe d   interplane   struts   and   swaged 

Span  of  tail  plane  and  elevators   18  ft.  0  1:1. 

Chord  of  tail  plane  and  elevators  6  ft.  0  in.  streamline   wires.      The    struts   are   faired   off    throughout 

Height    overall 13  ft.  0  in.  their    whole    length    by   means    of    light   wooden    fairings 

Length  overall   39  ft.  8  in.  covered  with  fabric.      Single  bracing  is  employed,  but  the 

Gap  of  main  planes   .                                                       7  ft.  3  in.  wjng  structure  is  so  designed  that  all  the  main  lift  wires 

Area  of  main  planes    022     sq.  ft.  are  duplicated  through  the  incidence  wires,  that  is  to  say, 

Area  of  ailerons   128     sq.  ft.  tnat  jf  a  front  ]jft  wire  were  shot  away,  the  load  normally 

Area  of  tail  plane    ....     48.4  sq.  ft.  •  d   b      thi         j       would   b      transmitted    through    the 

Area  of  elevators    36.8  sq.  ft.  -v 

Area  of  rudder   24.5  sq.  ft.  incidence   wire   to   the    rear    spar    bracing.     Ailerons    are 

Area  of  fin   10     sq.  ft.  fitted  to  the  trailing  edge  of  both  top  and  bottom  planes. 

.  The  wings  are  covered  with  Irish  linen  sewn  on  to  all  the 

ribs,  and  doped  in  the  standard  manner.     The  wings  are 

The  following  are  the  principal  weights:  built  up  of  ribs  made  Qn  a  patented  aluminum  girder  con- 
Weight  of  machine   (light)    4,300  Ibs.  struction,  the  top  plane  being  in  three  sections,  and  the 

Petrol^  120)   gallons ...      866  Ibs.  bottom  wing  in  four  sections.      The  inside  sections  of  the 

bottom  plane  are  built  into   the  bodv,   and   are   spcciallv 

Water   (13%)    gallons    13o  Ibs.  •  ' 

Pilot                 180  ibs.  designed  to  take  the  engine  units,  landing  gear  and  plat- 
Two  Passengers    380  Ibs.  forms    for   standing  on   whilst   attending   to   the   engines. 

Guns     70  Ibs.  The  main  wing  spars  are  of  spruce,  spindled  to  an  "I  " 

Ammunition                                                                                          Ibs.  section       The    ribs    are    bnilt            of    spruce    flalls,vs    and 

Bombs     1,083  Ibs. 

stamped   aluminum   ties.      1  liese   are    riveted   together   to 

Total  flying  weight 7,200  Ibs.      form   a   correct   girder   construction   and   are  exceedingly 

Main  planes  surface  loading  (fully  loaded)   . . .  7.825  lbs./sq.  ft.      strong.     The  internal  compression  struts  are  of  steel  tube, 
Nominal  engine  loading   lo.o      Ibs./h.p.          fitting  on  to  special  socket  bolts  which  also  take  the  brae- 


MULTI-MOTORED  . \I.KO1M..\NKS 


ing  plates  for  tin-  internal  bracing  ties.  The  inti  rn.-il 
bracing  ties  .-in-  formed  of  swaged  steel  rods  with  in.-i 
rluni-il  iiids  .mil  in  designed  l»  take  tin  t»t:il  drift  nn  the 

Willis   win  ii   tin-  machine   is   diving   at    limiting   velocity. 

The  trailing  edges  of  the  planes  art  compost  d  ,.|  ,>\  il 
steel  tubing,  securely  fasti-neil  to  tin-  ril  s.  Tin-  bracing 
plate  and  strut  attaelmient  on  tin-  wings  are  extremely 
lie  it  and  simple.  Tile  eml  of  tin-  struts  are  lilted  with  a 
snitalile  hemispherical  enil  which  tits  into  a  specially  de- 
signed cup  headed  dolt,  the  bolt  also  forming  the  attach 
ment  for  the  bracing  plate.  This  method  of  construction 
is  patented. 

Engine  Units 

Tin-  power  is  supplied  by  two  •_':>(>  h.p.  Galloway  B.ll.l'. 
Motors,  driving  din-et  two  airscrews  9  ft.  6  in.  in  diam 
i  ter.  The  engines  are  mounted  on  special  M-plv  and 
spruce  engine  mountings  which  are  l>uilt  into  the  renter 
sections  of  the  liottom  wind's,  forming  an  extremity  lif(lit 
and  rigid  lias,-.  The  main  petrol  tank  is  mounted  inimi- 
iliatelv  l><  hind  tin  engine,  anil  behind  the  petrol  tank  is  the 
oil  tank.  The  radiator  is  mounted  in  front  of  the  engine, 
and  the  whole  unit  is  carefully  faired  off  to  reduce  head 
resistance.  A  small  auxiliary  petrol  tank  is  mount*  d  on 
the  top  plane  just  ai;ove  the  power  units  and  is  used  for 
running  the  engine  when  on  the  ground  and  netting  off. 
Tin  petrol  is  fed  from  the  main  tank  to  the  auxiliarv  petrol 
tank,  or  direct  to  the  carlmrctors  of  the-  engine  by  means  of 
a  positive  pump  driven  by  a  small  windmill.  The  main 
tanks  are  provided  with  dial  petrol  level  indicators,  which 
;l\  r.  id  from  tin-  pilot's  seat.  It  may  be  as  well  to 
point  out  here,  that  practically  am  existing  type  of  engine 
can  lie  easily  accommodated  in  this  machine.  Any  engine 
from  •.'()()  h.p.  to  .inn  h.p.  being  suitable,  machines  of  this 
type  have  been  fitted  with  Rolls- Koyce.  Sunbeam  and 
dreen  Motors,  with  very  satisfactory  results.  Tin-  engine 
controls  are  conveniently  placed  at  eaeh  side  of  the  pilot, 
the  two  dependent  throttle  controls  being  on  the  pilot's 
right  hand  side,  and  the  magneto  controls  on  the  left  hand 
sidi  The  engine  controls  can  IK-  moved  together  or  inde- 
pendently, as.  for  example,  when  a  sharp  turn  is  required, 
one  throttle  ean  be  left  open  and  the  other  closed,  so  that 
the  engine  thrust  helps  the  turn.  I.cvers  are  also  pro- 
vided for  adjusting  the  carburetors  for  altitude. 

Body 

The  body  of  the  machine  is  of  the  usual  box  girder  con 
strurtion.  with   spruce   rails   and  struts  and   swaged  steel 


rod.s  for  bracing.  The  body  rails  are  stiffened  by  IIH  .-HIS 
Ii  wood  formers  in  the  Standard  Airo  in  inner. 
This  construction  makes  the  rails  extremely  strong  and 
obiiates  the  tendency  ot  the  rails  to  warp.  The  body  is 
of  a  good  streamline  lorm  and  proinlcs  ample  accommo- 
dation for  (In-  enw  and  the  bombs.  The  nose  of  the 
fuselage  is  eon  red  with  ::  ply  wood  and  the  decks  and 
iNimh  compartment  are  lornnd  ot  the  same  material.  Un- 
rest ot  the  body  being  eoiered  with  doped  fabric  carried 
OUT  stringirs  to  preserie  the  shape.  To  permit  the  rear 
gunner  to  tire  underneath  the  tail,  a  sp,  ,-ial  ^  at  i,  m.idi  in 
the  floor  through  the  rear  coekpit,  and  a  long  hole  is  ar 
ranged  in  tin  floor  through  which  a  good  view  downward 
and  backwards  is  obtained.  When  it  is  not  rei|iiin  d  to 
use  this  opening,  it  is  covered  hi  means  of  a  sliding  dooT. 
Steps  are  provided  in  the  side  of  the  body  and  a  small  light 
steel  ladder,  hung  from  the  side  of  the  machine,  enables 
the  crew  to  climb  easily  into  their  pl.i 

Tail  Unit 

This  consists  of  an  adjustable  tail  plane,  the  angle  of 
in. -nli  nee  of  which  ean  be  varied  by  the  pilot  whilst  in 
flight,  by  means  of  the  patent  Avro  tail  adjusting  gear. 
The  elevators  are  hinged  to  the  trailing  edge  of  the  tail  in 
the  usual  manner.  The  fixed  fin  is  fitted  on  top  of  tin- 
body .  and  hinged  to  the  stern  post  is  a  large  bal 
rudder.  All  the  empennage  members  are  built  up  of 
spruce  and  steel  tubing  and  covered  with  doped  fabric. 
The  tail  is  braced  by  streamline  steel  wire*. 

Controls 

The  elevator  and  aileron  control  is  of  the  wheel  and 
column  type.  The  large  hand-wheel  being  mounted  ver- 
tically in  front  of  the  pilot  on  the  top  of  the  rocking  col- 
umn. The  rudder  in  operated  by  means  of  foot  bar  in  the 
usual  manner.  All  control  surfaces  are  actuated  by  means 
of  flexible  steel  cable  passing  over  ball  bearing  pulleys. 

Landing  Gear 

The  landing  gear  in  of  uni<|u<  design,  weight  and  head 
resistance  having  lx-en  cut  down  to  the  absolute  minimum 
without  sacrificing  strength.  The  landing  gear  consists  of 
two  wheels  mounted  on  tubular  steel  axles,  which  are  at- 
tached by  means  of  ball  joints  to  the  body.  The  landing 
shock  in  taken  through  a  special  shock  absorbing  strut  as 
usually  employed  on  Avro  machines,  and  there  is  a  diag- 
onal behind  this,  taking  the  backward  loads  imposed  when 
landing  and  tax y  ing  on  the  ground. 


Hear  view  of  the  Avro  twin-motored   Itumliiiifr  Hiplanr. 


K 


F 


5      o 


LAW50N  TYPE'Cl 

TWIN  LIBEBTY  MOTOI2CD 

AEQAL  TPAN5POCT 


Sca.le  of    l^eet 


s       a       10       i?       14       1 


Mclaughlin 


64 


MULTI-MOTORED  AKKui'l. .\.\K> 


Lawson   Aerial   Transport 

The  giant    I  .aw  son   '    (      I   "  biplane   was  designed   from    i  front  and   rear  of  the  cabin.       On  the  left  su|.    of  the  cabin 

strictly  commercial   point   of   v  i,  w  forward  of  the  wings  an  entrance  door  is  provided.      Tins 

The  fuselage  is  built  to  accommodate   :il  pass,  Hi;,  rs  and  door    is    of    such    proportions    that    the    usual    method    of 

all   the   details   of   its   construction   and    performance   char  climbing  or  crawling  into  the  machine   is  done  awav   with 
acteristics   take   into   consideration   the   s  ,|,l\    and   comfort  P      .     , 

of  the  pass,  liters.  .        . 

Dual  controls  arc   provided   at    tli<    lorward   ,  nd   of   the 
I  he  seats  an    naililv    detachable  and  sleeping  quarters:  .. 

cabin.     <  out  ml    wheels    are    is      in    diameter    ind    ar, 

installed   for  a   fewer  number  ol    passengers   when  cruising 

mounted   on    a    tube    e\li  nding    from    one    side    of    the    bod) 
for    considerable    disl.-im  ,  s 

.....  '"    "'c    other.       1  he    wheels    control    the    ailerons    and    ele- 
I  he  ten,  ral   specifications  of  the   I. aw  son  Air    transport  .      . 

vators,  and   the    usual    f,Mit    bar   is    BMO    for   the    ruddi  rs 

I  -I       arc  as   Follow  s :  , .. 

All  control  surfaces  are  interconnected  and  cables  doubled 

General  Dimensions  |M   t|1(.  nj|(.,ons   wood   is  used   in  the  construction.      l-'or 

Span,  both   pl.mes    . . .  .M  ft.     0  In.  ,|,,.  st.-dili/.ers  and  el, -valors  both  wood  and  steel  an    p 

Chord,    both    planes     9  ft.     (i  in.  ....  .  .  .         ..  .         ..  .    .       a    .  . 

.     |  (i  ft      3  in  rudders  are  nearly  all  steel.      ror  night  Hying.  CMC 

I.ciurtli  ovtr.ill  it.     7  in.  lr'°  I'glds  arc  supplied  for  the  instrument  hoard,  interior 

ll.i.'lit    overall    U  ft.     0  in.      '  of  the  cabin,  and  the  wind's 

Areas  Tail  Group 

X,/.  fV.  The   fuselage  terminates   in   a   steel   tube   stern   post    to 

Main  planes,  including  ailerons  .  .I.TINI  which  is  attached  a  rcar  spar  of  the   lower  tail   plane  and 

Aill'r""s    (l)  also  tail  skid.      The  tail,  of  the  biplane  tvpe.  is  adjustable 

Stal.ili7.ers    (  .')     17iJ 

i)iiri<     .  ,,  5-$  to  counteract  any  ofVCmMM  in  balancing  which  may  in 

Kndilers    (:l)    45  s1"'-       "'"'    '"    the    large    si/c    of    the    machine,    passengers 

An~jeg  ln;l.v    move    freely    alxuit    the    fuselage    without    any    dis- 

Incidence   of  main    planes    3°  turbance  to  plane.       Uuddcrs  and  elevators  are  of  the  bal- 

Did.-dral     1°  anccd  ty|>e. 

i.haek    6e  Landing  Gear 

S    ,i,ili/er  settiii).'  to  \\\na  chord    0"  Ti       I       r  j      r  4  t  aa"  u 

I  he   landing  gear  is  composed  of  two  pairs  of  36     by 

We'ihts  8"  wheels  carried   on   large  streamlined  steel  tube   struts. 

M  icliinc    fully    loaded  .. 1^,000  Ibs.  T|1(.v   ;lrt.   attached   under  each  engine   in   such  a   way   as 

Performances  to  evenly  take  up  the  landing  shocks  with  a  minimum  of 

('limit  iii  10  minutes  with  full  loud 4,000  ft.  strain  to  the  wings  and  fuselage. 

luijr    14,000  ft. 

( lliilinjr   alible    1  to  8  Engines 

In,  I  duration    4  hours  Two   Ig-rylinder   I.ilx-rty   engines  are  used.      They   arc 

completely  enclosed  in  nacelles  at  either  side  of  the' fuse 

Main  Planes  loge. 

I      S.   A.   .">   winu'  section   is   used.      Main  planes  are  in  Engines  are  placed  in  pusher  position  with  profilers 

n   sections        The  outer  center  section  extends  between  M)'    in    diameter    revolving    in    opposite    directions.      They 

the  outer  struts  of  either  engine  nacelle.      The  two  lower  rest  on   large   ash   beds   internally   braced   by   steel   tubes. 

center    sections    run    from    the    fuselage    to    outer    engine  Gas    tanks    are    located    in    the    nacelles.      Kngines    are 

!•    struts.  equipped    with    separate   controls    to   the    pilot's   cotnpart- 

Fuselage  ment,  where  they  may  IK-  operated  separately  or  together. 

-    its  arc  placed  at  windows  at  each  side  of  the  body,  Effective  milliters  are   provided   which  add  greatly   to  the 

and   an   aisl,    Itctwcen  the  seats  allows  passage   from  the  comfort  of  the  passengers. 


/  ' 


IIIUII 


THE  FRENCH  CAUDRON  TWIN-MOTORED  BOMBING  BIPLANE 


A  front  view  of  a  Caudron   R   11    French   Bombing   Biplane.     This  machine  is  a  three   (3)    seater  and  is  driven  by  two   Hispano- 

Suiza  motors. 


French  Caudron  Biplane  equipped  with  two  Hispano-Suiza  motors. 


The  Caudron  R  11   type  of  French  Bombing  Biplane.    Twin  motored,    it    carried    two    and    sometimes    three    men.     The    nacelle 

projects  considerably  in  front  of  the  plane  thereby  insuring  a  good  view. 


66 


MULTI-MOTORED  AKKOI'LAM.S 


157 


The  Friedrichshafen 
Twin-Motored  Biplane 


This  machine  is  ;i  weight  carrying  type  and  was  used 
for  bombing  purposes.  It  iniriii.-illv  carried  a  crew  of 
four.  The  cot  -kpits  wire  intercommunicating,  so  thnt  the 
personnel  could  change  plan  s.  etc. 

The  tnt.-il  weight  of  tin-  empty  machine  is  5930  pounds. 
load  —  •-.'?'..'(>  M>s.  Maximum  load  —  8616  Ibs. 


sq.  ft. 


General  Description 

The  general  (lesion  of  the  machine  is  shown  in  the  at- 
tached  drawing,  which  gives  plan  and  front  and  side  ele- 

vations. 

The  principal  dimensions  arc  as  follows: 

Spat,     ..........................................   78  ft. 

M  .ixiiiiiini   ehnnl    ................................     7  ft.  fl  in. 

Gap     ...........................................     7  ft 

Dihedral   illicit-   in   the  \.-rti.-al  plain-   .............      ly,' 

Dihedral   :IML'|I-   in   the   hnri/.iint.il   pi  me    ...........      6* 

•nain   planes   ......................  934.4 

\n-;i  nf  upper  111.  mi   planes   without   flap   .........  490 

Area  of  lower  niiiin  planes  without  flap   ..........  451.4  " 

I.  o  nl    per    si|ii:irr    fm>t    ..........................      9.2+  His. 

\Veinht   per  horse   pimer    ........................    16.6  His. 

\rr  i  of  (lap  of  upper  wing  .....................  21-6     «!•  ft. 

llalancc   area    ...................................      1  .8 

of  ll.ip  on  lower  v>  ing  ......................  16 

Ilillanee    an-a    ...................................       1.56 

Tulal  area  of  lived  tail  planes   ...................  47.6 

I   urea  of  elevator-.    .........................  3i 

H.il.uice  area  of  one  elevator  ....................      1.7 

Ana   of    (in    ....................................  iO 

.if    rudder    ................................  19.3 

II.  il  am  i    area  of  rudder   .........................  3 

Maximum  cross  section  01  body   .................  19.2 

Horizontal   area  of  body   .............    ..........  133 

Vertical    area   of   liody    ..........................  131.9 

over  all    .............................  .  ..  4?  ft 


The  machine  is  built  up  upon  a  central  section,  to  which 

attached   the  forward  and   rearward   portions  of  the 

fuselage  and  the  main  planes.     This  central  section  com- 

prises the  main  cell    :r  caliin  of  the  body,  containing  the 

tanks,  bomlis.  etc.      It  also  embraces  the  engines  and  the 

tral    portion    of    the    upper    and    lower    planes.     The 

latter,  together  with  the  engine  struts,  are  largely  built  up 

of  still  tube,  as  is  also  the  landing  gear. 

Tin  central  portion  of  the  body,  which  measures  4  ft. 
across  by  I  ft.  S  in.  in  height,  consists  of  a  box  formation 
made  of  plywood,  strengthened  by  longerons  and  diag- 
onals, anil  transversely  stiffened  by  ply-wood  bulkheads. 
The  bulkhead  farthest  forward  acts  as  an  instrument 


board,  behind  which  are  side  by  side  the  seats  of  the  pilot 
and  bis  assistant.  The  former  has  a  fixed  upholstered 
si  at.  whilst  that  of  the  latter  is  folding,  consisting  of  a 
light  steel  tubular  framework  with  a  webbing  backrest. 

I  nderneath  these  two  seats  is  the  lower  main  petrol 
tank.  Behind  this  cockpit  the  body  is  roofed  in  with  ply 
wood,  the  rear  part  of  which  roofing  is  detachable  so  as  to 
give  access  to  the  second  main  petrol  tank,  which  is  at  the 
rear  end  of  the  main  body  section.  By  this  means  a  small 
caliin  or  covered  passageway  is  provided,  at  each  side  of 
which  are  the  racks  for  the  smaller  bombs. 

Central  Portion  of  Wings 

The  central  and  non-detachable  portion  of  the  upper 
plane  has  a  span  of  19  ft.  5  in.,  whilst  at  each  side  of  the 
nacelle  the  lower  plane  fixed  portion  measures  7  ft.  8  in. 
The  main  wing  spars  in  this  central  portion  arc  of  steel 
tube,  roughly  2  in.  in  diameter,  with  a  wall  thickness  of 
1/16  in. 

These  spars  are  braced  by  steel  tubes  arranged  in  the 
form  of  an  X,  the  manner  in  which  the  bracing  tubes  arc 
attached  to  the  main  spars  being  shown  in  the  sketch 
Fig.  1. 

The  lugs  are  built  up  by  welding,  and  are  pinned  and 
riveted  in  position,  the  joint  being  of  the  plain  knuckle 
type. 

The  upper  surface  of  the  lower  plane  is,  so  far  as  the 
central  section  is  concerned,  covered  in  with  three-ply 
wood. 

In  this  portion  the  main  ribs  are  of  three-ply,  with 
spruce  flanges.  Between  each  main  rib  is  a  cut-away  rib, 
the  design  of  which  is  shown  in  the  sketch  Fig.  2.  This, 
unlike  the  main  ribs,  is  one  piece  of  wood,  and  not  built  up. 
For  the  greater  part  of  its  length  it  applies  to  the  top 
surface  only,  being  cut  away  to  pass  clear  of  the  cross 
bracing  tubes. 

The  plane  is  further  stiffened  with  transverse  members 
consisting  of  three-ply  panels  between  each  rib  strength- 
ened by  grooved  pieces  top  and  bottom.  The  latter  are 
attached  as  shown  in  the  sketch  Fig.  .S,  and  the  attachment 
of  the  flanges  of  the  main  ribs  is  shown  in  Fig.  4. 

The  central  section  of  the  up|>er  main  plane  is  in  one 
piece  and  is  covered  top  and  bottom  with  fabric.  In  order 
to  facilitate  the  reinovnl  of  the  engines,  detachable  panels 
measuring  1  ft.  1 1  \'»  in.  long  by  1  ft.  8  in.  deep  are  let  into 
the  trailing  edge  immediately  over  the  engine  bearers. 
These  panels  are  socketed  in  front,  and  at  the  rear  are 


Line  drawings  of  the  Twin-motored  Friedrichshafen  Bombing  Biplane. 


Sketches  showing  details  of  construction  of  the  Friedrichshafen  Bomber. 

68 


.MlI.Tl-MOTOKI.l)   AKKOl'I.ANKS 


B8 


juiliril    up   at    tin-    trailing   edge    with    I      section    sheet    steel 
clips  anil  l.olts. 

The   struts   which  connect    the   top  of  tin-   nacelle   to   the 
uppi-r  plain-  art    tiilinl.-ir  and  of  streamline   section,  as  are 
also    tin-   engine    bearer    strut-..       A    section    of   on.     of    tin- 
latter  is  ^ivi  n  in   I  I  IT-  -"'-      'I'll'1  tliit-knc.ss  of  the  wall  is  mi. 
sixteenth   of  an   inch. 

The  method  of  attaching  the  lower  i-nil  of  tin-  engine 
struts  to  the  tuhular  steel  spars  is  shown  in  the  sketch  Fig. 
<;.  from  whi.-h  it  will  be  seen  that  a  weldc-d  Y  socket  it 
us<  d  and  secured  hv  a  pin  joint,  the  ends  of  the  pin  acting 
as  -meliorates  |cir  the  attaehinent  of  tin-  bracing  wires. 

'I'his  sketeli  also  shows  the  lugs  which  respectively  sup- 
port the  detachable  portion  of  the  main  planes  an. I  tin- 
vertical  strut  of  the  landing  chassis.  The  engine  hearer 
struts  are  pushed  into  the  i  socket  and  pinned  in  position, 
the  pins  lieinit  afterwards  hra/.ed  into  the  socket.  At  their 
upper  ends  the  engine  struts  are  (ixed  to  the  top  plane 
spars  with  pin  joints,  as  shown  in  Figs.  7  and  8,  the  attach- 
ment differing  according  to  the  number  of  wire  bracings 
that  art-  to  he  taken  to  each  joint. 

Construction  of  Wings 

The  detachable  portions  of  the  wings  are  fixed  to  the 
renter  section  by  pin  joints,  one  part  of  which  is  shown 
in  Fig.  t>,  the  male  portion  being  represented  in  Fig.  9. 
The  chord  of  the  wing  in  the  line  of  flight  varies  from 
approximately  7  ft.  8  in.  to  ~  ft.  .'.  in.,  and  the  wing  sec- 
tion is  shown  shaded  in  I'ig.  10.  In  order  to  provide  a 
basis  of  comparison  the  l(  A.I  .  \^  wing  section  is  super- 
imposed and  drawn  to  the  same  scale. 

The  main  spars  are  placed  one  meter  apart,  the  front 
spar  being  -J7'-'  iiims.  in  the  rear  of  the  leading  edge.  Both 
spars  are  of  the  built  up  ln>x  type,  as  shown  in  Figs.  11 
and  I  •-'.  Tin-  former  is  the  leading  spar  and  the  latter  the 
rear  spar.  These  spars  arc  of  spruce,  and  each  half  is 
furnished  with  several  .splices,  so  that  the  greatest  single 
1'iigth  of  timber  in  them  is  not  more  than  11  ft.  The 
splices,  which  occur  in  each  half  alternately,  are  of  the 
plain  bevel  type  about  1 .1  in.  long  and  wrapped  with  fabric. 
A  t.ibric  wrapping  is  also  applied  at  short  intervals  along 
the  spar. 

Internal  cross  bracing  between  the  main  spars  is  af- 
forded by  steel  tube  cross  memlxT.s  and  cables  attached  us 
shown  in  the  sketch  Fig.  9. 

Tin-  main  spar  joint  consists  of  a  steel  plate    1!)  mms. 
thick  embedded  in  the  spar  end  and  held  in  position  by   ~> 
bolts,  which   pass  through  a  strapping  plate  surrounding 
,|   of   the   spar.      This   plate   also   carries   the   attach- 
ment for  the  bracing  cable  and  is  furnished  with  a  spigot 
which  locates  the  bracing  tub*-.      It  will  be  seen  that  at  this 
point  the  spar  is  provided  with  ta|M-rcd  pat-king  pii 
hard  wood  glued  and  held  in  position  by   fabric  wrapping. 
The   main    ribs    are    placed    :i(i()   mms.    apart.       Between 
them  are  auxiliary   formers,  consisting  of  strips  of  wood 
•.'i>    mms.  x  in   mms.    thick,    which    run    from    the    leading 
to  the  rear  spar.      The  main  ribs  consist  of  ply  wood 
-ockcttcd    into    grooxed    spruce    llangcs.    which    are 
tapered  off  as  shown  in   Fig.    k  except  where  they  are  met 
by  a  longitudinal  stringer.     The  leading  edge  is  solid  wood 
moulded   to  a   semi-circular   section   of   approximately   OS 
.  d:ameter.     Where  the  rib  web  abuts  against  it,  pack- 


ing pieei  s  are  glued  i  ach  side.  Hetwieii  the  main  spars 
the  web  of  the  rib  Is  dn  id<  d  In  thr  .1  strips  into 

lour  panels  and  in  each  of  tlnse  it  is  perforated,  hiving 
an  edge  til  round  about  7-  mms.  wide. 

As  shown  in  1  -'ig.  !>.  the  upper  flange  of  the  main  ribs  is 
carried  char  of  the  hading  spar  by  means  of  packing 
pieces.  In  the  case  of  the  rear  spar,  packing  pieces  arc 
also  used  under  the  rib  flange  ns  shown  in  Fig.  12. 

The  lower  main  planes  for  a  width  of  about  2  ft.  3  in. 
at  their  inner  end  an-  covered  as  to  their  top  surfaces  with 
three  ply  wood. 

The  interplnne  struts  arc  attached  to  the  main  spars  by 
joints  of  the  type  shown  in  Fig.  I  k.  This,  it  will  be  seen. 
follows  the  typical  (uriiian  practice  of  partially  universal 
jointed  mountings  for  the  cable  attachments.  At  the 
points  of  attachment  of  these  strut  joints,  suitably  tapered 
packing  pieces  of  hard  wood  surround  the  spars,  which  at 
these  points  arc  also  wrapped  with  fabric. 

Struts 

Outside  of  the  center  section  the  interplane  struts  are  of 
wood  built  up,  ns  show  n  in  the  section  Fig.  1.1,  of  five  sepa- 
rate pieces.  The  curved  portions  arc  of  timber  which  has 
not  yet  been  identified,  but  is  apparently  of  poor  quality. 
The  cross  web  is  of  ash.  The  strut  is  wrapped  at  fre- 
quent intervals  with  strips  of  fabric  and  is  fitted  with  a 
socket  joint  of  the  type  shown  in  Fig.  16.  The  outer  pair 
of  struts  are  of  smaller  section  than  the  main  struts,  but 
are  built  up  in  a  similar  manner.  Their  section  is  125 
mms.  x  10  mms 

Ailerons 

The  framework  is  principally  of  welded  steel  tube 
wrapped  with  fabric. 

A  notable  point  is  the  thick  section  of  the  leading  edge 
of  the  balanced  |x>rtion,  us  shown  in  Fig.  17. 

Fin  and  Fixed  Tail-Planes 

The  framework  of  these  is  steel  tube  and  in  the  case  of 
the  tail-planes  wooden  stringers  running  fore  and  aft  are 
arranged  at  intervals.  The  tail-planes  are  supported  by 
diagonal  steel  tubes  of  streamline  section,  on  the  under 
side  of  which  sharp  steel  points  are  welded  to  prevent 
these  stays  being  used  for  lifting  purpose*. 

Elevators  and  Rudders 

Tin-  framework  in  each  ease  is  of  steel  tube,  the  main 
tube  being  35  mms.  in  diameter  and  the  remainder  15  mms. 

Bracing 

Throughout  the  wings,  both  internally  and  externally, 
the  bracing  is  by  means  of  malt  is)  rand  steel  cable. 

Fuselage  (Rear  Portion) 

At  the  after-gunner's  cockpit  the  section  of  the  fuselage 
has  a  rounded  top.  which  is  gradually  smoothed  down  into 
flat.  The  section,  for  the  greater  part  of  the  length,  U 
rectangular,  and  the  frame  is  built  up  in  the  usual  man- 
ner with  s<|iiare  section  longerons  and  \crticals.  the  joints 
being  arranged  as  shown  in  Fig.  18.  The  cross  bracing 
wires  along  the  sides,  top,  bottom,  and  diagonal  are  of 
steel  piano  wire  and  are  covered  with  strips  of  fabri. 


The  inside  of  the  front  cockpit. 


View  looking  down  the  inside  of  the 
fuselage,  showing  trap  door  and  after- 
gunner's  folding  seat. 


Flo.  19. 


Flo.  It. 


FIG.  12. 


Details  of  construction  of  Friedrichshafen  Bomber. 
70 


Fie.  23. 


Mn.TI-MOTOKKI)  A  KK<  HM.ANKS 


71 


shown  in  this  sketch,  where  they  In  adj  ic.-nt  to  tlir  fabric 
fuselage  covering. 

Tin-  vertical  and  liori/.ontal  compression  members  are 
located  by  spigots.  Tin-  joint  consists  of  «  plate  which 
completely  Mil-rounds  the  longerons,  its  two  mil-.  being 
rhcted  together  to  torin  a  diagonal  bracing  strip.  1  or  tin- 
last  few  liit  ;it  tin-  tail  the  fuselage  is  covered  with  thin 
three-ply. 

Tin-  fuselage  is  coMTcd  with  f.-ilirii-,  wliicli  is  held  in 
position  l>\  i  1. icing  iindrrni-atli  and  is  consri|iiciitly  hodilv 
n  movable. 

'1'ln-  lliKir  of  tin-  after  gunner's  cockpit  is  elevated  above 
the  hottoin  of  the  fiis'  l.i^i  I  iniiiediatel  V  underneath  this 
cockpit  is  a  large  trap  door,  shown  liy  dotted  lines  in  the 
plnn  view  of  the  aeroplane.  This  is  hinged  at  its  rear- 
ward end  and  furnished  with  two  large  celluloid  windows. 
It  is  held  in  its  "  up  "  position  by  a  long  spring  and  a  snap 
clip.  No  me  ins  could  he  found  bv  which  it  could  he  ii\.  ,1 
in  its  dosed  position.  As  footsteps  are  provided  for  all 
the  cockpits,  this  trap  door  is  evnlentlv  not  intended  for 
ingr.  *s  ,il(|  e^n-ss.  It  rould  he  employed  in  connection 
with  a  machine  pin  tiring  backwards,  as  in  the  (iotha.  but 
no  iiiachini  gun  mounting  was  fixed  in  this  machine  for 
this  pur). 

Tin-  rear  portion  of  the  fuselage  is  attached  to  the  cen- 
ter section  of  the  body  liy  a  clip  at  each  corner.  This  is 
shown  in  1  ig.  1!'.  The  rear  portion  carries  a  male  lug, 
which  engage  s  with  the  two  eyes,  and  is  held  in  position 
,fhs  holt.  lour  other  l>olts  in  tension  pass  through 
the  sheet  metal  clip,  as  shown  in  the  sketch.  In  each  case 
the  hit's  arc  furnished  with  sheet  steel  extensions  which, 
as  shown  in  the  sketch  Fig.  19.  are  sunk  flush  into  the  top 
mid  bottom  surfaces  of  tin-  fuselage  longerons  and  are 
there  held  with  three  holts.  The  corner  joint  is  welded 
•ii  i-l.  and  there  is  an  additional  diagonal  sheet  steel 
point  which  serves  the  secondary  purpose  of  providing  an 
anchorage  for  the  bracing  wires. 

As  this  fuselage  joint  is  level  with  the  plane  of  rota- 
tion of  the  propellers,  it  is  armored  both  on  the  nacelle  and 
on  the  rear  portion  of  the  fuselage  with  a  hinged  covering 
of  stout  sheet  steel  lined  with  felt.  A  plate  of  armor  a 
foot  wide  also  extends  down  each  side  of  the  nacelle  at  this 
point. 

Forward  Cockpit 

This  is  attached  to  the  main  body  by  four  bolts  with 
dips  similar  to  those  just  described.  It  consists  of  a  light 
ien  framework,  covered  throughout  by  three-ply. 

The  cock-pit  can  be  divided  off  from  the  main  cockpit 
by  means  of  a  fabric  curtain.  Its  occupant  is  provided 
with  the  folding  seat,  and  manages  a  gun  and  the  bomb- 
dropping  gear. 

Engine  Mounting 

The  engine  bearers  have  the  section  shown  in  Fig.  20, 
and  arc  each  built  up  of  two  pieces  of  pine  united  by 
s.  On  their  top  surface  they  are  faced  with  ply- 
wood, and  at  the  bottom  with  ash.  A  strip  of  ash  applied 
to  the  upper  outer  corner  of  the  bearer  gives  it  an  "  L" 
section,  and  has  screwed  into  it  the  threaded  sockets  for 
tb«  set  screws  of  the  lower  part  of  the  engine  fairing. 
The  engine  bearers  taper  sharply  at  each  end.  They  are 


mounted  on  the  "  V  "  struts  by  means  of  acctvh  in  wehhd 
brackets,  constructed  as  shown  in  sketch.  Fig.  J  1 .  These. 
it  will  IK-  seen,  are  of  box  form,  and  form  a  liner  round 
tin  streamline  tube. 

The  engine  cow  linn  is  a  particularly  fine  piece  of  work, 
and  two  views  are  given  in  sketches  22  and  23.  Tin- 
lower  portion  is  attached  to  the  i  ngine  hearer*  by  set 
screws,  but  the  up|M-r  part  is  readily  d«  tachable,  being 
furnished  with  turn  buttons.  Tins  cowling  allows  the 
cylinders  of  the  engine  to  be  exposed  to  the  air.  A  large 
scoop  is  placed  in  front,  so  as  to  permit  a  free  flow  of  air 
OUT  the  bottom  and  sides  of  the  craiikchamucr,  whilst  at 
the  rear  three  Inrgc  trumpet  shaped  cowls  arc  provided  so 
that  a  draught  of  air  is  forced  against  the  craiikca.s<-  in  the 
neighborhood  of  the  carburetor  air  intake.  In  the  rear  the 
fairing  abuts  against  the  propeller  nave,  whilst  in  front  it 
is  attached  to  the  radiator.  It  will  IK-  noticed  that  at  each 
side  of  the  radiator  are  narrow  air  scoops,  the  object  of 
which  is  to  promote  a  draught  past  the  oil  tank  and  front 
cylinder  heads. 

Engines 

Theraiotors  are  the  standard  260-h.p.  Mercedes  with  six 
cylinders  in  line.  Full  details  of  this  engine  have  been 
published,  and  it  is  only,  therefore,  necessary  to  notice 
one  or  two  points  in  connection  with  the  installation. 

A  new  departure  is  the  interconnection  of  the  throttle 
and  ignition  advance  controls.  This  is  carried  out  in  tin- 
manner  illustrated  diagrammatical ly  in  Fig.  24.  It  will 
be  seen  that  a  considerable  movement  of  the  throttle  can 
be  made  independently  of  the  ignition  advance.  In  the 
Mercedes  carburetor  the  throttle  is  so  arranged  that  it 
cannot  be  fully  opened  near  the  ground  without  providing 
too  weak  a  mixture,  and  it  is  thought  possible  that  the  full 
ignition  advance  is  not  obtained  until  this  critical  opening 
is  reached. 

On  several  German  bombing  aeroplanes  grease  pumps 
for  lubricating  the  water  spindle  have  been  found.  Fig. 
25  shows  the  design  as  fitted  to  the  Friedrichshafen.  It 
consists  of  a  ratchet  and  pawl  operated  grease  pump,  se- 
cured by  a  bracket  to  one  of  the  engine  struts,  and  worked 
from  the  pilot's  cockpit  by  a  lever,  and  a  stranded  steel 
cable  passing  over  a  pulley,  the  pawl  being  returned  by  a 
long-coiled  spring. 

The  exhaust  pipe  is  of  new  design,  although  it  incor- 
porates the  well-known  expansion  joints  attached  to  the 
flanges.  It  is  fitted  with  what  amounts  to  a  rudimentary 
silencer,  whereas  in  previous  machines  of  a  similar  type  to 
the  Friedrichshafen  an  open-ended  exhaust  pipe  was  used. 

Radiators 

Each  radiator  is  provided  with  an  electric  thermometer 
fitted  into  the  water  inlet  pipe,  us  shown  in  sketch.  Fig. 
•J7,  these  thermometers  being  wired  up  to  a  dial  on  the 
dashboard,  which  is  furnished  with  a  switch,  so  that  the 
temperature  of  either  radiator  can  be  taken  independently. 

The  radiators  consist  of  square  tubes  to  the  number  of 
4134.  and  measuring  roughly  0  mms.  each  way. 

The  radiator  block  is  V  shaped  in  plan,  and  each  is 
provided  with  a  shutter  which  covers  up  a  little  more  than 


Construction     details     of     the     Friedrich 
shafen  Bomber. 


Kio.  32. 


Main  landing  chassis,  tail  skid  and  ma- 
chine gun  mounting  in  the  front  of  the 
fuselage. 


MILTI-MOTOKKl)   AKKOl'I.ANKS 


a  third  of  tin-  cooling  surl  u  i  .  This  shutter  is  fitted  with 
;i  stop,  so  Unit  when  fully  n|)i-iifd  it  lirs  ill  tilt-  line  ot 
flight  of  tin-  :ii-ro|)laiir.  It  is  o|n-in-d  or  clos.  ,1  :u  , -onling 
In  ciri  iimstances  liy  tin  year,  show  M  in  tin  sketch.  I  || 
of  «  Inch  the  h  indie  is  iniiunted  on  the  roof  of  the  nacelle, 
iniinriliatelv  behind  the  pilot's  seat.  Three  positions  ar< 
provided  for  the  handle,  which  operates  tin  two  shutters 
simultaneously  Iv  means  ot  return  eahles. 

Iminediati  1\  .ilio\e  the  main  radiator,  in. I  let  into  tin- 
upper  main  plain-  between  the  front  spar  ami  the  I.  idiii:: 
i  .In.  .  is  a  small  auxiliary  tank,  illustrated  11 
This  is  furnished  with  a  trumpet  shaped  \ent  in  the  direc- 
tion of  the  line  of  flight,  and  is  furnisln  d  with  two  oiith  Is, 
one  to  the  Inad  of  the  main  radiator,  ami  the  other  to  the 
water  pump.  The  function  of  this  tank  is  evidently  to 
•it  the  pump  from  priming. 

Oil  Pump 

Tin  main  supply  of  oil  is  carried  in  sumps  forming  part 
of  the  hase  chamber.  A  secondary  supply  of  oil.  from 
which  a  small  fresh  cliarije  is  drawn  at  every  stroke  of  tin- 
oil  pump,  is  contained  in  a  cylindrical  tank  supported  1>\ 
brackets  from  the  engine  struts,  and  placed  immediately 
In-hind  the  radiator.  This  tank  has  a  capacity  of  25 
liters  ;,  i  _.  gallons.  Kach  tank  is  furnished  with  a  glass 
level.  w  Inch  is  \  isihle  from  the  pilot's  seat . 

Petrol  Tanks 

The  two  main  tanks  which  are  placed,  one  under  tin- 
pilot's  seat  and  the  other  at  tin-  top  rear  end  of  the  nacelle, 
contain  •J711  liters  ."i!»i..  gallons  each,  and  arc  made  of 
hri".  I  ich  is  provided  with  a  Maximal!  level  indicator, 
which  employs  the  principle  of  n  Hoat  operating  n  dial  by 
means  of  a  cable  enclosed  in  a  system  of  pipes. 

A  hand  pump  is  fitted  conveniently  to  the  pilot,  and 
pressure  is  normally  provided  by  the  pumps  installed  in 
each  engine.  An  auxiliary  tank,  holding  approximately 
l:i  gallons,  is  concealed  iii  the  upper  main  plane,  not  imme- 
diately over  the  nacelle  but  a  little  to  the  left  side.  This 
auxiliary  tank  is  fitted  with  n  level,  as  shown  in  Fig.  29, 
which  is  visible  from  the  cockpit.  The  auxiliary  tank 
nppiars  to  be  used  only  for  starting  purposes.  It  is  cov- 
ered with  a  sheet  of  fabric  held  in  position  by  "patent 

.'  Ts." 

Engine  Controls 

Kiinning  from  each  engine  to  the  nac-elle  is  a  horizontal 
!iit.  containing  the  various  engine  controls. 
ion  showing  the  arrangement  of  these  inside  the  fair- 
ina  is  itiv.n  in  the  sketch.   Fig.  30.      The  leading  edge  of 
the  streamline  easing  consists  of  a  steel  tube,  to  which  are 
weld-d   narrow    steel   strip    brackets,   to   the   rear  end   of 
which  are  bolted  thinner  strips  which  are  hinged  in   front 
to  the  tuln-.     The  whole  is  then  enclosed  in  a  sheet  alumi- 
num fairing. 

Through  the  leading  tube  passes  the  throttle  control  rod 
h  engine,  the  two  throttles  being  worked  either  to- 
gether or  independently   by   the  ratchet    levers,  shown   in 
I.     Tlnse  are  mounted  on  a  shelf  convenient  to  tin- 
pilot  s   left   hand.     This   control    requires   a   considerable 
number  of  bell  cranks  and  countershafts,  but  was  notice- 


ably   trie    t  re. in    backlash.       The    throttle    is   opened    by    tin- 
pilot  pulling  the  levers  towards  him. 

On  tin  dashho-ird  an  !«..  r.  volution  counters  and  two 
air  pressure  indicators.  Tin  metal  parts  ol  tins,  dials  are 
p-iinti  d  n  il  lor  tin  li  It  i  nuiin  am!  i;n  .  n  for  tin  right,  and 
tin  same  coloring  applies  to  the  magneto  switches,  one  of 
which  contains  a  master  switch  which  applies  to  both 
in  mm  tos  on  both  i  urines. 

Piping 

The    various    sv  stems    of    piping   are    distinguished    by 
1     ii.g   painted   dilnr.  nt    color.,   thus   the    petrol    pi|M-s   are 
*  lute,  arrows    licing   also    painti  d   on    (him    to    show    the 
direction  of  How;  air  pressure  pipes  arc  blue,  ami  |  i 
for  cable  controls  gray. 

Propeller 

The  prop  Hers  are  each  8.08  meters  in  diameter  and 
are  made  of  nine  laminations,  which  are  alternately  wal- 
nut and  ash,  except  one  which  appears  to  be  of  maple. 
The  propeller  has  the  last  20  ins.  of  its  blade  edged  with 
brass.  The  pitch  is  approximately  1.8  nieti  rs  nnd  the 
maximum  width  of  the  blade  '-'-JO  millimeters. 

Controls 

Only  one  set  of  control  gears  is  fitted,  but  as  pointed  out, 
tin-  seating  accommodation  is  so  arranged  that  any  of  the 
crew  can  take  charge  if,  and  when,  necessary. 

The  elevator  and  aileron  control  is  shown  in  sketch  Fig. 
32.  It  consists  of  a  tubular  steel  pillar  mounted  on  a 
cranked  cross  bar  at  its  foot.  The  ailerons  are  worked 
by  cables  passing  over  a  drum  on  the  wheel,  whence  they 
descend  through  fiber  (juidcs  on  the  cross  bar  to  another 
wheel  mounted  on  a  countershaft  below,  from  which  they 
are  taken  along  inside  the  leading  edge  of  the  lower  wing 
and  finally  over  pulleys  up  to  the  aileron  levers  on  the 
top  plane.  The  latter  are  partially  concealed  in  slots 
let  into  the  trailing  edge  of  the  wing.  The  upper  and 
lower  ailerons  arc  connected  by  means  of  pin  jointed 
tubular  steel  struts  of  streamline  section. 

It  will  l-.e  observed  from  Fig.  82  that  a  locking  device 
whereby  the  elevator  control  enn  l>c  fixed  in  any  desired 
position  is  tilted,  and  consists  of  a  slotted  link  which  can 
be  clamped  by  a  butterfly  nut  to  the  control  lever.  This 
link  is  hinged  to  a  small  bracket  attached  to  the  panel 
below  the  pilot's  seat. 

Fig.  M  shows  the  rudder  control,  from  which  cables 
are  taken  over  pulleys  and  through  housings  in  the  nacelle 
and  finally  to  the  end  of  the  fuselage.  The  cranked  rud- 
der bar  is  of  light  steel  tube  and  is  arranged  to  be  placed 
in  the  pivot  box  in  either  of  two  positions.  It  is  furnished 
with  light  steel  tubular  hoops  which  act  as  heel  rests  nnd 
are  adjustable.  A  locking  clip  is  fitted  on  the  floor  of 
the  cockpit  so  that  the  rudder  can  be  fixed  in  its  neutral 
position. 

A  novel  type  of  trimming  gear  is  an  interesting  item 
of  the  control.  Movement  of  cln  elevator  control  from 
the  normal  upright  |x>sition  of  the  stick  is  made  against 
the  tension  of  one  of  two  springs  which  can  be  alternately 
extended  and  relaxed  by  means  of  a  winch  connected  to 
them,  as  shown  in  the  diagram.  Fig.  81.  Normally  these 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


springs  tend  to  bring  the  control  stick  back  to  a  central 
position,  in  which  the  elevator  lies  flat,  but  if  one  of  the 
springs  is  tensioned  by  winding  up  the  winch  in  clock- 
wise direction,  the  position  to  which  the  stick  will  tend 
to  come  when  released  will  be  such  as  to  set  the  elevator 
at  a  positive  angle.  This  winch  gear,  which  is  illustrated 
in  Fig.  3:5,  is  mounted  on  the  right-hand  side  of  the  nacelle, 
and  is  therefore  under  the  command  of  the  pilot's  com- 
panion. 

The  crank  is  furnished  with  a  locking  pawl,  which 
engages  with  a  ring  of  small  holes  bored  in  the  plate  of 
the  winch.  The  steel  springs  used  in  conjunction  with 
this  apparatus  are  some  3  ft.  long  and  about  %  in.  in  diam- 
eter. The  inscription  behind  the  winch  read :  — 

Nose  heavy  —  Right  wind. 

Tail  heavy  —  Left  wind. 

Landing  Gear 

As  might  be  expected,  the  landing  gear  on  this  machine 
is  of  massive  proportions.  Two  vertical  streamline  sec- 
tion wood-filled  tubes  descend  from  the  center  section 
wing  spars,  immediately  under  the  engine,  to  a  bridge 
piece  or  hollow  girder  made  of  welded  steel.  Through 
an  oval  hole  in  this  girder  a  short  axle  carries  two  965 
mms.  x  150  mms.  wheels  (38  in.  x  6  in.).  These  work  up 
and  down  against  the  tension  of  a  bundle  of  steel  springs 
about  1/2  in.  'n  diameter  and  made  of  wire  approximately 
1-16  in.  thick. 

The  steel  girder  is  extensively  pierced  for  lightness, 
and  the  edges  of  the  holes  are  swaged  inwards.  The  axle 
is  prevented  from  moving  sideways  by  plates,  and  is  pro- 
vided with  short  steel  cables  which  act  as  radius  rods  and 
connect  it  to  the  front  of  the  girder.  The  whole  of  the 
box  girder  is  covered  in  with  a  detachable  bag  of  fabric, 
which  extends  up  to  the  small  cross  bar  mounted  imme- 
diately above  the  girder. 

Mudguards  are  provided  behind  each  landing  wheel  for 
the  purpose  of  preventing  any  mud  or  stones  dislodged 
by  the  wheels  from  coming  in  contact  with  the  propellers. 

From  the  front  and  rear  of  the  box  girder  streamline 
tubes  are  taken  to  the  ends  of  the  main  wing  spars,  where 
they  abut  against  the  nacelle,  and  these  diagonals  are 
further  braced  with  streamline  steel  tubes.  Both  the 
vertical  and  diagonal  tubes  are  held  in  split  sockets  so  as 
to  be  easily  replaceable  if  damaged. 

In  addition  to  the  four  main  landing  wheels,  a  fifth  is 
mounted  under  the  nose  of  the  fuselage.  This  wheel  is 
760  mms.  x  100  mms.  (30  in.  x  -1  in.).  It  is  mounted  on  a 
short  axle,  which  is  capable  of  sliding  up  and  down  slots 
in  its  forks  against  a  strong  coil  spring,  and  it  is  also 
capable  of  a  certain  amount  of  lateral  movement  along 
its  axle,  also  against  the  action  of  two  small  coil  springs. 

The  tail  portion  of  the  fuselage  is  protected  by  a  fixed 
skid  made  of  wood  but  shod  with  a  steel  sole.  This  is 
fitted  with  a  small  coil  spring  contained  inside  the  fuse- 
lage. 

Wiring 

The  whole  of  the  wiring  system  on  the  machine  is  very 
neatly  carried  out.  There  are  three  main  systems ;  firstly, 
the  ignition  wiring,  which  is  contained  for  the  most  part 
in  tubes  of  glazed  and  woven  fabric ;  secondly,  the  heating 


system,  for  which  the  wires  are  carried  in  flexible  metal 
conduits ;  and,  thirdly,  the  lighting  system,  in  which  a  thin 
celluloid  protective  tubing  is  used.  Wires  are  run  from 
the  nacelle  along  the  leading  edge  of  the  upper  planes 
to  points  level  with  the  outermost  strut.  Here  they  termi- 
nate in  a  plug  fitting  placed  behind  a  hinged  panel.  Ap- 
parently lamps  are  intended  to  be  served  by  the  circuit. 
Immediately  in  front  of  the  pilot's  seat  a  universally 
jointed  lamp  bracket  is  mounted  on  the  outside  of  the 
nacelle.  The  exact  purpose  of  this  lamp  is  not  known, 
as  it  could  not  illuminate  any  instruments. 

Armament 

Both  the  forward  and  rear  cockpits  are  furnished  with 
swivel  gun  mounts  carrying  Parabellum  machine  guns. 
These  mounts  consist  of  built-up  laminated  wood  turn- 
tables working  on  small  rollers,  and  carry  a  U-shaped 
tubular  arm  for  elevation.  This  arm  is  hinged  to  a 
plunger  rod  working  through  a  cross  head,  and  arranged 
so  that  the  arm  is  normally  pulled  down  flat  on  the  turn- 
table by  a  coil  spring.  The  plunger  can  be  locked  in 
any  of  a  series  of  positions  by  means  of  a  bolt  operated 
by  a  hand-lever  through  a  Bowden  wire.  A  second  lever 
allows  the  turntable  to  be  locked  at  any  desired  point.  A 
perforated  sheet-metal  shield  protects  the  cross  head  and 
spring.  Small  shoulder  pads  are  fixed  on  the  turntables, 
of  which  that  in  the  forward  cockpit  has  a  diameter  of 
2  ft.  1Q1/2  in.,  whilst  in  the  rear  the  diameter  is  3  ft.  y2  in. 

The  after-gunner  is  prevented  from  damaging  the  pro- 
pellers by  two  wire  netting  screens,  supported  by  tubular 
steel  brackets,  placed  on  either  side  of  his  cockpit.  These 
are  sketched  in  Fig.  36. 

In  addition  to  these  two  guns,  provision  is  made  for 
mounting  a  third  in  front  of,  and  to  the  right  of,  the 
pilot's  cockpit,  where  it  could  be  managed  by  his  com- 
panion. For  this  purpose  a  clip  is  provided  immediately 
under  the  coaming  of  the  nacelle,  and  the  handle  of  this 
protrudes  through  a  slot  in  the  dashboard.  The  clip 
works  on  the  eccentric  principle,  and  appears  to  be  self- 
locking.  Its  construction  is  shown  in  detail  in  Fig.  37. 

A  rack  for  Very  lights  is  mounted  on  the  outside  of 
the  nacelle  convenient  to  the  pilot's  companion. 

INSTRUMENTS 

Airspeed  Indicator 

Considerable  interest  attaches  to  the  fact  that  this 
Friedrichshafen  Bomber  is  the  first  enemy  machine 
brought  down  which  has  been  found  provided  with  an 
airspeed  indicator.  This  is  of  the  static  type,  embody- 
ing a  Pitot  head  of  the  usual  type.  The  indicator  has  a 
dial  of  large  size,  and  is  altogether  a  much  more  bulky 
instrument  than  any  for  a  similar  purpose  used  in  British 
machines.  An  investigation  of  its  mechanism  is  being 
made. 

Altimeter 
This  is  of  the  usual  type,  reading  to  8  kilometers. 

Level  Indicator 

This  is  a  somewhat  crudely  made  device,  employing 
two  liquid  levels,  as  indicated  in  the  diagrammatic  sketch 


MULTI-MOTORED  . \KHoiM.. \M-.S 


75 


Fig.  38.  It  will  be  seen  th.it  tin-  reading  uixcs  tin-  pilot 
an  exaggerate  i!  idea  of  tin-  angle  nf  mil.  Tin  glass  tiiln-s 
art-  sealed  u]>,  and  contain  n  d  irk  blur  liquid. 

Revolution  Counters 

Tin-  dials  i;i\c  readings  from  ;(IKI  to  HIiici  r.p.ni.  The 
sector  In  tw.eii  l.;ou  and  l.'.oii  i,  painted  Mark,  and  these 
figures  an  marked  with  luminous  compound,  as  also  is 
tin  indicating  hand. 

Air  Pressure  Gauges 

Tlu-M-  r.-ad  from  u  to  o.~.  kilogrammes  per  square  ccnti- 
meter.  Thin  is  a  r.  d  mark  ajr-iinst  tin  figure  0.25  kg. 

Electric  Thermometer  Dial 

This  dashboard  instrument  consists  of  a  box-type  me- 
ter, the  dial  reading  from  II  to  loo  ,|,  -  (  The  figures  0 
and  ':•  are  accentuated  liy  red  marks.  A  switch  at  tin 
side  of  the  l>o\,  having  positions  marked  1  and  "2,  allows 
the  temperature  of  either  radiator  to  be  read. 

Petrol  Level  Indicators 

These  art  ,.l  the  \Ia\iinall  type,  and  employs  a  float 
immersed  in  a  tubular  guide  in  the  tank.  This  float  com- 
municates iu  motion  to  a  tinker  working  over  a  circular 
dial,  by  means  of  i  thin  cord  passing  over  pulleys.  These 
are  incasid  in  pipes,  which  are  under  the  same  pressure 

as    (he    tank. 

Electric  Heating  Rheostat 

This  is  illustrated  in  Fig.  39.  It  is  marked  Aus  (off), 
Schwach  ,  xxiak>.  Stark  (strong).  There  arc  two  sep- 
arate resistance  coils.  ,  imMing  th.  rheostat  also  to  per- 
form the  function  of  a  change-over  switch. 

Wireless 

The  machine  is  internally  wired  for  wireless,  and  the 
left  hand  engine  is  provided  with  a  pulley  and  clutch 
for  drix-ing  the  dynamo.  Reference  to  Fig.  22  will  show 
that  this  is  designed  to  be  mounted  on  a  bracket  carried 
by  the  outside  front  engine  bearer  strut,  and  that  the 
engine  fairing  is  molded  to  receive  it. 


Bombs  and  Bomb  Gear 


At  each  side  of  the  cox  end  in  passage  «.iy  in  the  nacelle 
are  l.omb  racks  capable  of  holding  five  *3-pomid,r  (12 
kg.  )  bombs. 

I  nderneath  the  naeell.  an  ,  -irrieil  two  large  tubular 
ir.m.s.  lilted  with  cradles  of  steel  cable,  and  furnished 
with  the  usual  form  of  trip  gear. 

These  racks  would,  it  is  l.elicxcd,  l>e  capable  of  SUp- 
portin-  a  :;IMI  kg.  bomb  apiece.  The  homlis  carried,  how- 
c\cr.  exidently  xary  with  the  radius  of  action  ,,,,r  which 
the  aeroplane  has  to  operate.  The  Inr^e  racks  are  not 
permanently  attached  to  the  nacelle,  but  |x  he  r. 

moved  as  required. 

Inside  the  front  cockpit  from  which  the  release  of  the 
bombs  is  coiiductid.  there  are  s,  MII  triers  for  the  small 
bomb  racks  and  two  levers  for  the  lar^e  l>oml>  trips.  The 
cables  for  this  gear  are  carried  under  the  floor,  and  are 
painted  different  colors  for  distinction. 

Bomb  Sight 

The  homb  sjjfht  carried  on  tin  machine  presents  no  new 
features,  and  is  of  the  ordinary  German  non-precision 

type. 

Fabric  and  Dope 

Two  entirely  different  kinds  of  fabric  are  employed  in 
the  I'riedrichshafcn  machine.  The  wings  are  covered 
with  a  low-grade  linen  of  the  class  which  is  employed  on 
most  of  the  enemy  machines.  It  is  white  in  color.  Com- 
pared with  that  of  British  fabrics,  the  tensile  strength  is 
fairly  good. 

This  fabric  is  covered  with  a  cellulose  acetate  dope, 
and  is  camouflaged  in  large  irregular  lozenges  of  dull 
colors,  including  blue-black,  dark  green,  and  earth  color. 

The  other  fabric,  which  is  applied  to  the  fuselage,  tail 
planes,  rudder,  elevator  fin,  and  landing  gear,  is  appar- 
ently a  cheap  material,  much  inferior  to  British  fabrics 
designed  for  a  similar  purpose.  This  fuselage  fabric  is 
dyed  in  a  regular  pattern  of  lozenges,  the  colors  being 
hardly  distinguishable  from  black.  The  dope  is  acetate 
of  cellulose. 


GOTHA 
TWIN  ENGINE  BIPLANE,  TYPE  GO.  G; 


TA/1KS. 


76 


Mil  /n-.M(  >T(  )H  KI )   A  KK(  )IM  ,.\  X  KS 


77 


\    Ciotha   twin -iiuitured    I'li-hrr   Hipl.inr. 


The  Gotha  Twin  Motored  Biplan 
Type  GO.  G5 


Tl..-  ,1,  tails  of  tliis  machine  do  not  differ  to  any  great  fiord 

•xt.-nt  from  tlms,-  of  th<-  usual  German  construction.  Ow 

Thr  p-nt-ral   drtails  of  this   plane  are:  KnKi"<-  rrnt.-rs    ...............      II  ft. 

,     „  ,.  Knirlncs   (Mercedes)     ...........   360  h.p.  each 

.spa,,     ,!„,,    plan,-)     ,,v,-r    tips    of      P]    ft.  S,-t    l.m-k   of   plan,.    .............        4' 

I'roprll.-r    (diainrtrr)    ...........      10  ft.  2   In. 

Span    (l,,,tt,.,n   plan,-)  ^^  Qf  undpr  ca  whw|g        rf  f,  ,n 

Imp     ...........................         *    II* 


"  «•  2'/»  'n.  to  7  ft.  6  In. 
11  fi   ' 


f,    ,% 


rhrec    virw^    nt     the    German    Gotha 
twin-motored  Biplane. 


GERMAN    A.E.G 

TWIN  ENGINED  520\? 

BOMBING  BIPLANE 


MULTI-MOTORED  AKKoi'I. .\M.s 


Two       ii  w.    n,"    Hi.-    (Irrinni      \.     I''..    ('• 
twin  -inoton  (I    lli|i|,iiir. 


The  German  A.  E.  G.  Bombing  Biplane 


Fundamentally  tlie  A.  E.  G.  bomber  resembles  the 
(lot  ha  biplanes.  In  dimensions,  however,  the  two  ma- 
chines iliHVr  considerably,  the  Gotha  being  somewhat 
larger.  Also  the  A.  K.  (i.  lias  its  two  airscrews  placed 
in  front  of  the  main  planes,  whereas  in  the  Gotha  they 
are  "  pusher  "  screws.  As  in  tlir  (iotlia.  the  wings  of  the 
A.  I.  (i.  are  swept  back  at  a  5°  angle  and  are  also  placed 
at  a  dihedral  angle,  which  appears  to  be  greater  in  the 
bottom  than  in  Ihe  top  plane.  The  span,  it  will  be  seen 
from  the  scale  drawings,  is  the  same  for  both  planes,  and 
amounts  to  .1 7  ft.,  while  the  overall  length  is  about  30  ft. 
<!  in  ;  chord,  7  ft.  0  in.;  area  800  sq.  ft.;  gap,  8  ft.  6  in. — 
7  ft.  ~>  in.  The  ailerons,  which  are  of  a  peculiar  shape, 
are  fitted  to  the  top  plane  only,  and  are  operated  by  a 
crank  lever  working  in  a  slot  in  the  plane.  This  arrange- 
ment would  appear  to  be  in  general  favor  with  German 
designers,  whereas  it  is  rarely  or  never  met  with  in  Allied 
••chines. 

The  tail  planes,  which  are  of  the  monoplane  type,  con- 
sist nf  fixed  stabilizing  planes  with  an  area  of  SO  sq.  ft., 
and  a  vertical  fin,  to  which  are  hinged  the  elevators  and 
rudder  respectively.  Both  elevators  and  rudder  have  for- 
ward projections  in  order  to  partly  balance  them,  thus 
relieving  the  pilot  of  a  certain  amount  of  the  strain  of 
working  the  controls.  Maximum  height  of  rudder,  6  ft. 
9  in.;  area  17  sq.  ft.;  maximum  span  of  elevators,  12  ft. 
ii  in.;  total  area,  25  sq.  ft.  A  tail  skid  is  fitted  under  the 
sti-rn  of  the  fuselage,  and  is  sprung,  not  by  means  of  rub- 
ber shock  absorbers  as  is  usually  the  case  with  our  ma- 
chines, but  by  means  of  coil  springs.  The  same  is  the 
case  with  the  landing  chassis,  where  coil  springs  arc  also 
us<  d  instead  of  rubber.  Whether  this  "  indicates  a  short- 
age of  rubber  "  in  Germany,  or  whether,  for  machines  of 
such  large  dimensions  and  heavy  weight,  it  has  been  found 
mnrr  suitable,  it  is  not  possible  to  say. 

As  already  mentioned,  the  material  used  in  the  construc- 
tion is,  with  very  few  exceptions,  steel,  practically  the 
only  parts  made  of  wood  being  the  ribs  of  the  main  planes. 


The  main  spars  are  in  the  form  of  steel  tubes,  which  ii 
rattier  surprising  in  view  of  the  fact  that  about  the  worst 
use  to  put  a  circular  or  tubular  section  is  to  employ  it  as 
a  beam  laterally  loaded,  since  much  of  the  material  of 
such  a  section  will  be  situated  at  or  near  the  neutral  axis, 
where  it  is  adding  weight  without  contributing  greatly 
towards  the  strength.  Possibly  the  tube  has  been  chosen, 
in  this  instance,  for  reasons  connected  with  the  manufac- 
ture rather  than  from  considerations  of  structural  suit- 
ability. The  method  of  attaching  the  root  of  the  main 
spar  to  the  center  section  of  the  top  plane  is  shown  in 
one  of  the  sketches.  The  short  length  joining  the  center 
section  spar  and  root  of  wing  appears  to  be  turned  from 
the  solid,  hollowed  out  at  one  end  to  receive  the  center 
section  spar,  and  having  machined  on  the  other  a  forked 
end  to  receive  the  root  of  the  main  spar.  The  strut  socket. 
which  resembles  those  usually  found  on  German  machines, 
is  attached  to  it  by  welding. 

Like  the  rest  of  the  machine,  the  fuselage  of  the  A.  K.  (i. 
bomber  is  built  up  of  steel  tubes,  this  material  being  used 
for  longerons  as  well  as  for  struts  and  cross  members. 
These  are  connected  by  welding  and  the  joints  are  stiff- 
ened and  anchorage  provided  for  the  cross  bracing  wires 
by  triangular  pieces  of  sheet  steel  welded  to  longerons 
and  struts. 

With  regard  to  the  accommodation  for  the  occupants, 
this  is  divided  into  three  divisions.  In  the  front  cockpit 
— at  the  extreme  nose  of  the  body — is  a  seat  for  tin- 
bomber,  who  views  the  ground  below  and  obtains  his  sights 
through  a  circular  opening  in  the  floor.  On  his  right  the 
bomber  has  a  rack  holding  bombs;  these  are  presumably 
not  of  a  very  heavy  caliber.  Under  the  center  of  tin- 
body  there  is  another  bomb  rack  carrying  the  heavier  pro- 
jectiles. Near  the  inner  ends  of  the  lower  plane  there 
are  fittings  for  an  additional  supply  of  bombs.  The  ma- 
jority of  the  bombs,  however,  arc  not,  so  far  as  it  is  pos- 
sible to  ascertain,  carried  under  the  body  and  wings,  but 
inside  the  body. 


80 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Curtiss  Model   18-B  Biplane 


After  the  successful  trials  of  the  Curtiss  Model  1 8-T  tri- 
plane,  the  two-seater  18-B  biplane  was  brought  out  by 
Curtiss  Engineering  Corporation.  The  biplane  is  built 
around  the  same  fuselage  and  power  plant  as  the  triplane, 
but  having  a  lesser  overall  height  the  gunner  has  a  wider 
area  of  fire. 

The  housing  of  the  engine  is  particularly  neat ;  it  is  en- 
tirely encased  with  the  exception  of  the  exhaust  stacks, 
which  are  streamlined.  The  removable  cowling  around 
the  engine  makes  the  power  plant  accessible  for  adjust- 
ments and  repairs. 

As  in  the  triplane,  all  interplane  cables  are  of  true 
streamline.  Where  cables  cross,  they  are  clamped  to- 
gether by  streamlined  blocks. 

Another  peculiarity  of  this  machine  is  the  employment 
of  ailerons  on  the  lower  plane  only.  These  ailerons  are 
operated  by  steel  tubes  running  through  the  lower  plane 
and  directly  connected  to  the  pilot's  control  stick.  This 
principle  entirely  eliminates  all  outside  control  cables  and 
rigging. 

Rudder  and  elevators  are  operated  by  levers  enclosed  in 
the  fuselgae  termination  thereby  doing  away  with  all  out- 
side control  cables.  There  are  no  external  braces  for  the 
stabilizer  or  fin. 

General  Dimensions 

Span,  upper  plane   37  ft.     5%  in. 

Span,  lawer  plane 37  ft.     5%  in. 

Length  overall    23  ft.     4       in. 

Height  overall   8  ft.  lOy.,  in. 

Chord,  upper  plane  0  ft.  54      in. 

Chord,  lower  plane  0  ft.  48      in. 

Stagger     0  ft.  16  9/16  in. 

Gaps, —  between  planes   5  ft.     0      in. 

Weights 

Pounds 

Weight,  fully  loaded  3,001 

Useful  load  1,013 

Performances 
(Altitude) 

Feet 

Service  ceiling 23,000 

Maximum   ceiling    23,7.50 

Climb  in  10  minutes  12,500 

Climb  in  10  minutes  (light  flying  load)   16,000 

(Speed) 

Highspeed   (m.p.h.)..    lfiO.5  158.5  157.5  155  152 

Altitude                      Sea  SflOO  10,000  20,000  15,000 

level          feet  feet  feet  feet 

Low  speed    (m.p.h.) . .     59             68.2  73.6  79.8  86 
Kconomical  Speed 

(m.p.h.)     80             85  92  100  118 

(Climb) 
Kate  of  climl, 

(ft.    per   minute)     ...2390          1690         1040        580        210 
Time  of  climb 

(minutes)     0  2.5  6.3          12.9          27 

(Endurance) 

Miles  Hours 

High  speed   (sea  level)    283  1.75 

Economical  speed  (sea  level)   536  6.7 

Main  Planes 

Planes  are  in  flat  span.  There  is  no  dihedral  nor 
sweep-back. 


Main  planes  are  in  five  sections.  Center  section  over 
the  body  30  in.  wide.  Outer  section  17  ft.  5%  in.  in 
span.  Overall  span  37  ft.  5%  in-  Lower  plane  in  two 
sections  at  either  side  of  the  body,  each  17  ft.  5%  in.  span. 

As  indicated  on  the  accompanying  line  drawing,  the  ribs 
are  spaced  about  6  in.  apart.  Instead  of  the  usual  two 
main  wing  beams,  the  Model  18-B  employs  five  main  wing 
beams,  the  idea  being  to  more  evenly  distribute  the  loading 
on  them. 

The  chord  of  the  upper  plane  is  54  in.  Forward  main 
wing  beam  located  9  in.  from  leading  edge.  Wing  beam 
over  the  rear  fuselage  and  interplane  struts  2  ft.  9  in. 
from  leading  edge. 

Chord  of  lower  plane  48  in.  Forward  main  wing  beam 
9  in.  from  leading  edge.  From  this  the  other  main  wing 
beam  members  are  spaced  75/16  in.  apart. 

Ailerons  on  the  lower  plane  have  a  very  high  aspect 
ratio,  being  13  ft.  5  1/16  in.  in  length  and  10%  in-  wide. 

Struts  over  the  fuselage  are  spaced  30  in.  apart.  From 
these  the  intermediate  interplane  struts  are  centered  6  ft. 
ll/>  in.  From  intermediate  struts,  outer  struts  are  cen- 
tered 7  ft.  81/2  in.  This  leaves  an  overhang  of  43%  in. 

Fuselage 

The  fuselage  is  of  monocoque  construction,  finely  stream 
lined.  Overall  length,  21  feet. 

Pilot's  cockpit  is  below  the  trailing  edge  of  upper  plane. 
Aft  of  the  pilot,  the  gunner's  compartment  is  arranged  so 
that  the  gunner  has  a  wide  range  of  fire  for  the  two  Lewis 
machine  guns,  one  of  which  is  located  on  a  rotatable  Scarff 
ring  surrounding  the  cockpit,  and  one  which  fires  through 
an  opening  in  the  under  side  of  the  fuselage. 

Landing  Gear 

The  track  of  the  landing  gear  is  595/s  in.  Wheels  26  in. 
in  diameter.  The  axle  is  located  441/4  in.  from  the  nose 
of  the  fuselage,  and  491/2  in.  below  the  center  line  of  en- 
gine. With  the  machine  in  flying  position,  the  center  of 
gravity  of  machine  occurs  at  a  point  16.6  in.  behind  the 
axle  of  landing  gear. 

When  at  rest  on  the  ground,  a  straight  line   from  the 
landing  wheels  to  the  tall  skid  makes  an  angle  of  1 1   de- 
grees 15  minutes  with  the  center  line  of  thrust. 
Tail  Group 

The  triangular  fin  is  3  ft.  in  length  and  3  ft.  6  in,  in 
overall  height.  Rudder,  46  in.  in  overall  height  and  31 
11/16  in.  in  width.  The  stabilizer  is  divided  at  either  side 
of  fuselage.  Maximum  deptli  at  the  body,  2  ft.  5  in. 
Maximum  span  overall,  10  ft.  10l/2  in.  Elevators  are 
18%  in.  in  width. 

Engine  Group 

The  engine  is  a  Curtiss  Model  K-12  engine. 

Two  Duplex  type  carburetors  are  used.  They  are  lo- 
cated between  groups  of  cylinders.  Carburetors  are  sup- 
plied with  an  auxiliary  altitude  hand-controlled  air  valve 
and  also  with  non-back-firing  screen. 

The  propeller  is  9  ft.  0  in.  in  diameter.  In  flying  posi- 
tion, the  tips  of  the  propeller  clear  the  ground  by  81/2  in. 
When  the  machine  is  at  rest  there  is  a  clearance  of  171/..  in. 
between  the  propeller  tips  and  the  ground. 


Ml -LTI-MOTOKKI)  AEROPLANE 


81 


The  Curtis*  "  Oriole  "   Biplane 

Tlu-   "Oriole"   was    brought    out    to    (ill    tin-    need   of   a  Main  Planet 

ni.-ii  liiin-  tin-  sol,-  |iur|iosf  of  which  is  tin-  carrying  ot    pas  |>t   for  tin    ccnti-r  section,  ninill  plnnrs  are  made  up 

si  liters  in   i  sit',   and  comfortable  manner.      A  door  is  pru  of  sections  similar  in  ->/<    .-iiui  ar..-i        Main  wing  sections 

v  iiled   tin   tin-   left   Mtlr  of   tin-   hotly    i  indica'.i  il   by   dashed  are  set  at  a  I1-  tli  vr'  '    ililnilr.il  jingle, 
lint- on  the  drawiiii:  i,  so  the  compartment  is  easy  to  get  into.  Portions  of   the    ni.-nn   planes   jirt-   flit    away    next  to  the 

Tin-   i;i  neral   speeitientiiins  an-:  bodx    anil   null  •.-  section   to   pt-rinit    wide   \ision   rnngt-   for 

General  Dimensions  passengers  ami  pilot. 

S'""'  '"'>""  '','•""•    '  Fuselage  and  Landing  Gear 

Snail,    lower    plain-     «'    ".   0   III. 

( 'lior.1.  Loth  plaii.-s   5  ft.  o  iii.  '  llr  ntOfft  is  v!*  ft.  X  in.  ill  overall  length.      IU  sec- 

L.-iiL'tli.    overall    .'A   ft.  il  in.  tion  is  oval,  .S  ft.  •„'  in.  liy  X  ft.  H  in.      With  tin    •  •iis-iin  .  tin 

H.-i-lit,   OMT.-I||         »  ft.  A  in.  fusel.-mr   «•  ialiis  :i.'-,  H>». 

Provision   is   made   fur  carrying  two  passengers  seated 

Weights  ^  ,,,),    |,v   ,|,1,.   i,,   ()„.   for«arcl   nn-kpit   Jinil   the   pilot   in   the 

r.    fnlh     I... -I    ,  """«  aft''r    '''^l1''-       C  ""lr"ls     l<K-nt'-'1     »'     P'1"1'-    "'^l"1    ""*? 

,-„!    |,m,|  '  ;i,;  Coiiipartnifiits   are   upholstereil    in   leather.      Large   wind 

N.I   uei^ht.  inrlinlin^  water    M-'l  s|,n  Ills  provide  protection  from  the  winil. 

Useful  Load  Because  of  the  deep  lio<ly.  short  struts  Jin-  list  il  on  the 

!'"»»'>•  landing  chassis.      \\'hei-ls  art-  •-'(!  in.  x  M  in.,  .spaced  0  ft. 

P»d  (43  «*)  tin.  apart. 

Oil    (I    (rals)     :W 

.,.|()|  l(jo  \\  ing  tips  nn-  provided  with  cnne  bow  skids,  In  low  the 

Passt-inrrr  or  .itlirr   |...ul   3iO  outer  wing  struts. 

Speed  Tail  Group 

M.l'.ll.        M.l'.ll.       M.l'.ll.  Stahiliascr  It)  ft.  1  .1  in.  in  span.  •>'  ft.  (i  in.  in  mnximum 

'"'ft-  width.      The   stahili/.er   is   tlivitletl    nnd    symmetrically   dis- 

M.IMMIIIIII    speed    -  8S.O  -" "  * 

Mniit.i.im  sp,.,.,|    475  5I.H  56.0  Pos«1  «»  «*"«  side  of  the  body. 

.niit-al   spt-ftl    60.0  64.5  71.0  Klev.-itors.   I    ft.  (5  in.  wide. 

Climb  '  '"  '-'  ft-  <;  in'  w'<ir  ;""l  :l  fl-  :1  '"•  "igh.      Rudder  sur- 

ffft  face  is  all  disposed  above  the  fuselage,  as  the  body-  termi 

(Timl.   (full  load)  in  10  minut,-  2,+75  natcs  jn  a  strean,iine  form.      Rudder  I  ft.  0  in.  high.  •-'  ft. 

It. id    of   i-linih.   per    iniiuite    400  fi   .^     ^.jjp 

Endurance  Engine 

Mil  ft        Hour* 

\t  lii-h  sn,',.ii  365  43  A   Curtiss   OX-5    Engine   is    used.     This    is   an   eight 

At  iTonnmiral  spee<l   393  6J  cylinder  "  V  "  type,  four  stroke  cycle  engine. 


Side  view  of  the  Curtiss  "  Hornet,"  model  18-B,  two-seater  biplane.     It  has  a  speed  of  163  m.p.h.  and  climbs  16,000  feet  in  10  min- 
utes, with  light  flying  load 


CHAPTER  III 
SINGLE  MOTORED  AEROPLANES 


The  Aeromarine  Training  Tractor 


The  Aeromarine  Training  Tractor 


This  machine  is  well  suited  for  training  purposes. 

General  Dimensions 
Span,  upper  plane   ........................  37  ft   0  in 

Span,  lower  plane    ...............................  33  ft!  0  in.' 

...........................................     6  ft.  Sin. 


6  ft.  6  in. 
Length  over  all   ..................................  25  ft.  6  in. 

V  i  eight,   empty    ..................................       1>300  ,bs 

Useful  load   .....................................         700  lbs 

Motor,   Aeromarine    ..........  100  h  p 

Speed   Range       ......................  ...'.'.'.'.'.'  .'.'.'  .'78^2  m.p.h. 


I  limb  in   10  minutes 


3)500 


Planes 


In  form,  the  wings  are  designed  after  the  R.  A.  F.  6 
pattern.  Leading  edge  of  planes  are  covered  with  thin 
veneer  to  maintain  the  correct  front  curvature. 

Ribs  are  of  lightened  section,  spaced  about  12  inches 
apart.  The  rib  webs  are  reinforced  between  lightening 
holes  to  protect  against  shear. 

Struts  are  hollowed  to  lightness  as  much  as  practical. 

In  the  internal  wing  bracing,  separate  wooden  struts 
and  not  wing  ribs  carry  the  drag  of  the  wings. 

Fuselage 

Longerons  are  of  large  section,  lightened  at  points  where 
the  strength  would  not  be  impaired.  Consideration  has 
been  given  to  the  rough  usage  to  which  the  bodies  of 
school  machines  are  subjected,  and  all  wires,  turnbuckles 
and  fittings  are  designed  accordingly. 

The  fuselage  is  22  ft.  6  in.  in  length,  2  ft.  6  in  in  its 
maximum  width,  and  3  ft.  6  in.  in  over  all  depth  at  the 

82 


pilot's  cockpit.     Both  cockpits  are  arranged  with  a  full 
complement  of  instruments. 

Tail  Group 

The  stabilizer  is  divided  and  mounted  on  either  side 
of  the  body.  In  design  it  is  of  the  double  cambered  type. 
The  sections  of  the  stabilizer  are  quickly  detachable  from 
the  fuselage. 

Elevator  planes  are  each  attached  to  the  stabilizer  by 
four  hinges.  From  tip  to  tip  the  elevator  planes  meas- 
ure 10  ft.  9  in.  across;  width,  2  ft.  5  in. 

The  rudder  is  of  the  balanced  type  and  of  streamline 
section.  The  frame  is  formed  of  steel  tubing.  From  the 
bottom  of  fuselage  the  rudder  reaches  a  maximum  height 
of  4  ft.  0  in.  The  balanced  portion  extends  1  ft.  3  in. 
forward  of  the  rudder  post,  and  the  main  portion  2  ft.  1 1 
in.  to  the  rear  of  pivot. 

Landing  Chassis 

Axles  are   li/.,  in.  diameter.     Between  the  wheels  the 
tube  is  134  in.  in  diameter.     Walls  of  the  axle  in  the  hubs 
are  8/16  in.     Hubs  have  bronze  bushings. 
Motor  Group 

Provision  is  made  for  the  installation  of  the  new  Aero- 
marine 8-cylinder  100  h.p.  motor.  The  gear  ratio  is  7 
to  4,  turning  an  8  ft.  4  in.  Paragon  propeller  with  a  6  ft. 
pitch  at  1400  r.p.m.  The  motor  is  4-cycle,  with  a  bore 
of  Sy2  in.  and  a  5%  in.  stroke. 

Delco  starter  and  ignition  are  provided  and  built  in  as 
an  essential  part  of  the  motor. 


THE   BELLANCA 

35  HP  ANZANI 

LIGHT 


of  f«.t 


3      4      s      e 


McLvMUb 


83 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Bellanca  Biplane,  .showing  the  neat  appearance  of  the  warping  wings  and  streamline  Locly 

The  Bellanca  Biplane 


The  light  passenger-carrying  Bellanca  biplane  has  been 
designed  to  answer  the  requisites  of  quick  get  away,  fast 
climb,  and  high  speed,  and  to  have  at  the  same  time  light 
weight,  the  ability  to  glide  at  a  flat  angle,  and  low  flying 
speed  to  insure  a  great  degree  of  safety  in  landing.  To 
these  qualities  are  added  the  item  of  moderate  cost  and 
ease  of  maintenance,  high-grade  construction  and  the  pos- 
sibility of  rapidly  assembling  and  dissembling. 

The  inventor  had  in  mind  the  idea  of  presenting  a  ma- 
chine which  would  be  of  universal  use  for  popular  flying 
as  well  as  for  training.  Careful  attention  was  given  to 
all  details  as  dictated  by  the  latest  research  and  accepted 
good  practice.  That  such  things  have  been  attained  the 
demonstrations  of  its  performances  seem  to  bear  out. 

On  his  first  flight  the  pilot  released  the  controls  when 
an  altitude  of  1000  feet  was  reached.  Perfect  stability 
and  high  climb  were  observed.  The  throttle  was  full  open. 
Without  touching  the  controls,  the  throttle  was  retarded  to 
diminish  the  power  about  50  per  cent,  and  the  machine 
proceeded  in  straight  horizontal  flight.  With  the  engine 
shut  off  the  machine  quietly  disposed  itself  to  a  flat  glide. 

Other  tests  of  the  machine's  speed  show  that  with  full 
power,  it  is  capable  of  85  m.p.h.,  and  by  throttling  the 
engine  the  speed  can  be  reduced  to  34  m.p.h.  The  value 
of  this  performance  will  be  better  realized  when  it  is  un- 
derstood that  the  Bleriot  and  Deperdussin  monoplanes  of 
similar  horse  power  have  a  speed  range  of  40  to  46  and 
40  to  48  m.p.h.,  respectively.  Favorable  comparison  will 
also  be  found  with  a  number  of  modern  machines,  both 
European  and  American,  with  100  h.p.  or  more,  which 
make  an  average  speed  of  70  to  80  m.p.h. 

In  climb  tests  the  Bellanca  biplane  ascended  to  3300 
feet  in  10  minutes  and  4600  feet  in  14  minutes,  with  the 
engine  throttled  down  to  1080  r.p.m.,  equal  to  18  h.p. 

With  the  engine  turning  at  1080  r.p.m.  the  machine 
made  a  speed  of  691/2  m.p.h.  in  three  consecutive  half- 
mile  flights  at  a  height  of  15  feet  from  the  ground.  The 
speed  mentioned  was  the  average  for  the  three  flights. 


WTith  the  engine  increased  to  1200  r.p.m.,  equal  to  24  h.p., 
the  climb  of  the  machine  increased  to  530  feet  per  minute 
and  the  horizontal  speed  was  76  m.p.m.  The  climb  was 
measured  by  means  of  a  barograph  and  aneroid. 

In  testing  the  gliding  quality,  the  pilot  began  a  glide 
from  an  altitude  of  4600  feet  at  a  distance  of  about  ten 
miles  from  the  starting  point.  With  the  engine  shut  off 
the  field  was  reached  and  passed,  and  it  was  necessary 
to  turn  back  and  glide  against  the  wind  toward  the  field, 
adding  two  miles  to  the  distance  traversed.  In  this 
manoeuver  a  time  of  8  minutes  and  5  seconds  elapsed  be- 
fore the  ground  was  touched.  In  this  glide  the  machine 
was  favored  by  a  wind  of  6  to  7  m.p.h.  The  incidence 
angle  indicator  showed  that  the  machine  was  gliding  at 
an  angle  of  5  degrees,  which  is  equal  to  a  ratio  of  1  to 
11.5. 

The  above  test  shows  that  in  case  of  a  forced  landing 
from  an  altitude  of  4600  feet,  the  pilot  will  have  ample 
time  to  select  a  landing  place  within  a  diameter  of  24 
miles. 

General  Description 

Best  selected  white  ash  is  used  for  the  principal  parts 
of  wings,  fuselage,  landing  gear,  etc. 

Brazing  and  welding  have  been  eliminated  wherever 
possible.  Care  has  been  observed  to  avoid  the  piercing 
of  longerons  and  other  vital  members. 

Safety  Factor 

The  factor  of  safety  of  lift  stresses  on  the  beams  of 
upper  and  lower  wings  is  16,  and  the  factor  of  drift 
stresses  is  14.  In  the  body  and  landing  gear  the  safety 
factor  of  the  weakest  point  is  12. 

Field  tests  have  shown  a  high  safety  factor  under 
difficult  conditions.  Even  in  snow  14  inches  deep,  the 
machine  never  met  with  difficulty  in  leaving  the  ground 
nor  in  landing.  In  diving  and  even  in  tail  spinning  tests, 
the  machine  was  quick  to  recover  itself,  confirming  the 
strength  of  sustaining  surfaces. 


SIM, 1. 1.   MOTOKK1)  AKKOI'L. \.\KS 


n 


Assembling  Facility 

In  actual  tests,  tin-  machine  was  dissembled  in  1 /,  min- 
nt.-s  and  re.-issciiihlcd  ready  to  fly  in  -JU  ininiitrs.  This 
id  in  is  expiditcd  liy  tin-  employment  of  a  -p. vial  turn- 
bucklc,  which  can  lie  loosed  and  detached  without  losing 

tin-    adjustment    of    tension,    so    that    a    simple    \emeiit 

restores     the    attacliiilrnt    of     the    cable     with     its    original 
adjustment. 

General  Specifications 

Span,   upper   pl.-inr    .'(i   ft.  II  in. 

Span,  lower  plain-    £0  ft.  6  in. 

Chord,   upper   plain-  I   ft.  (>  in. 

Chord,   lower   plane    .....  .'   It.   t  In. 

I  ...    I  40  sq.   ft. 

th   overall 17   ft.   7   in. 

Weight,   iiini-hini-    empty    400  Ills. 

I       '•'!    l""l    -' ,.373  II.-. 


Performances 


Maximum    Speed. 


Minimum    Speed 


IM« 

N     h.p.... 
[  18    h.p 


in  ft 

per  hour) 
83 
76 
70 
34 


M  ixiiiiiim   Cliint.iiiir   Spreil 


per  min.) 

fS5    h.p...        .  830 
I  j^    i  £W 

[18    h.p  .......   330 

Cli.linir    \nglc   ......................................    1  to  11.3 

Min.  h.p.  required  for  hori/.  mtal   Hight   ......................   6 

Main  Planes 

The  dynamical  stability  of  the  planes  is  almost  the  same 
a-  tin-  Kitl'el  :i-.'.  It  is  most  suited  to  high  speed  because 
of  it-  v.r\  small  drift  at  small  angles  of  incidence,  and 
l.eeau.sc  of  the  structural  advantages  afforded  by  the  sec- 
tion. 

Spars  are  of  ash,  having  a  safety  factor  of  1  t. 

Struts  between  planes  arc  of  streamline  section  of  con- 
stant depth  for  two-thirds  their  length.  Ends  taper  to 
the  strut  fittings. 

Controls 

Lateral  and  longitudinal  balance  is  operated  by  stick 
control.  The  rudder  is  balanced;  it  is  operated  by  tin- 
foot  bar. 

Lateral  control  is  obtained  by  warping  the  wings,  and 
it-  effect  is  so  immediate  as  to  require  but  a  slight  move- 
ment of  the  stick. 


Fuselage 

The  fuselage  is  of  good  streamline  form.     Ita  wooden 

I  r  mie  i-  of  IM.X  girder  construction,  braced  hv  cables  from 
the  pilot's  eoekpit  forward  and  with  wire  from  the  sam. 
cockpit  rearward.  The  nose  is  co\ered  with  aluminium. 
a  round  door  in  on,  side  giving  access  to  the  engine. 
The  reniamdi  r  i-  covered  with  linen.  do|M-d  and  varnislud. 
The  front  deck  i-  ..I  veni.r.  linen  entered.  The  body 
tapers  to  a  vertical  strut  edge  at  the  rear,  on  which  the 
rudder  is  hinged.  No  U.lts  pass  through  the  fuselage 
-pars,  a  simple  ami  light  fitting  making  this  possible.  In 
front  of  the  pilot  is  a  dash,  on  which  are  found  oil  sights, 
clock,  aneroid,  inclinometer,  and  incidence  angle  indi- 
cator. 

Landing  Gear 

The    chassis    i-    of    the    ordinary    V    type,    each    V    con 
sisting  of  two  ash  laminated  streamline  struts,  joined  to- 
gether by  steel  ami  aluminium  plates.      Rubber  shock  ah 
sorbcrs  bind  the  axle  to  the  struts. 

Tail  Group 

The  empannage  group  is  composed  of  a  non-lifting  fixed 
stabilizer,  to  which  is  fastened  the  elevator  flaps. 

The  attachment  of  the  stabilizer  is  such  that  it  is  easily 
detached  by  removing  four  cotter  pins. 

The  rudder  is  of  oval  shape  and  is  of  sufficient  area 
to  insure  complete  control  in  handling  the  machine  on 
the  ground. 

Engine  Group 

An  air  cooled  .1  cylinder  An/.ani  Y  type  35  h.p.  is  used. 
Its  weight  is  1*0  Ibs.  Propeller  6  ft.  7  in.  in  diameter 
and  5  ft.  9  in.  pitch.  The  engine  is  so  attached  as  to 
form  with  the  rest  of  the  body  a  perfect  streamline  form 
with  low  head  resistance. 

Only  part  of  the  cylinders  are  exposed,  which  are  effica- 
ciously cooled  by  such  a  flow  of  air  as  obtained  by  a  speed 
of  85  m.p.h. 

To  ascertain  the  complete  cooling  of  the  engine,  re- 
peated and  accurate  tests  were  performed.  The  engine 
was  first  tested  on  the  ground,  and  after  five  minutes'  run- 
ning, it  was  already  losing  15  |>er  cent,  of  its  initial  h.p. 
This  loss  was  increasing  as  the  engine  continued  to  work. 

On  the  contrary  when  the  machine  was  flying,  such 
power  loss  was  almost  completely  eliminated,  for  after 
from  40  to  6<>  minutes  of  flight,  no  over-heating  was  ob- 
served. 


The  Dellnnca  Biplane  in  flight 


CURTI55 

MODEL    JN4-B 
MILITARY  TRACTOR 


Scale   of   Feet 


-fe— 


86 


SI\(;i.K   MOTOHKI)   .\KK01M..\.\KS 


K7 


'II,.-  well  known  Curtiss  .INI,  cuuippcd  will.  ,,   Hispaiio-Sui/.a  motor.     This  type  of  |.|linr  was  used  extensively  for  training  pur- 

POM-S.      It    was  originally   powered    with   a   Curtis  OX   s  cylinder    motor. 


Curtiss   Model  JN-4D  Tractor 


Due  to  tlic  f.ut  that  tliis  machine  has  been  widely  used 
for  training  .m.ttnrs  both  IHTC  and  abroad,  the  JN  tvpr 
i-  prok-il.lv  the  la-st  known  of  all  the  Curtiss  models. 

It  is  comparatively  \i£\i[  and  for  its  useful  load  carry- 
ing rapacity,  is  very  compact. 

General  Dimensions 

'iii)r  S|uin  —  t'pper   Plane   ..................  43  ft.  7%  in. 

in^r  Spun       Lower   Plane    ..................  S3  ft.  11%  in. 

Depth  of  Wing  Chord   .......................  591^  |n. 

C.lp     lietucell      Wilier,      .........................     61%     jn 

Stagger    ....................................  16  in. 

Length  of  .Machine  overall   ...................  .'7  ft.  +  in. 

Height  of  Machine  overall   ...................  9  ft.  10%  in. 

AiiL'le  of    Ineiili-nee    ..........................  i    degrees 

Dihedral    Angle    .............................  1  ,|,.grec 

Swi-.-plm.-k    ..................................  0  decrees 

Wing  Curve    .................................  Kiffel    yo.   ,; 

Horizontal  Stahiliier  —  Anple  of  Incidence  ____  0  degrees 

Areas 

ind's     -  fpper     .....  .........................    167.94  ^   ft. 

-I^'wrr     .........................    149.«  sq.  ft. 

"s    (  l'|'l'«T)    ...........................   35.3  sq.   ft 

Horizontal    Stahiliu-r    ........................  28.7  sq.   ft. 

Verlieal    Stahilizer     ..........................   3.8  «,.   ft. 

Klevators   (each  11  «(.  ft.)    ...................   a  sq.  ft. 

Kiitlder    .....................................    U  sq. 

Total  Supporting  Surface   ....................   352.56 

Loading  (weight  carried  |«-r  sq.  ft.  of  support- 

ing  surface  )     ..............................   6.04   M.S. 

|MdlOf  (per  It.  H.  P.)    .....................   23.65    Ibs. 

Weights 

Net   Weight  —  Machine  K.inpty  ...............  1^80  Ibs. 

CirosN  \\'ci)rht  —  Machine  and  Load  ...........  3,13()  ll.s. 

I'seful  I^,a<l  ................................  550  n,s. 

Fuel     ...............................  130  ll.s. 

Oil     ..................  38  ll.s. 


I'ilot     165  Ibs. 

Passenger  and  other  load   217  Ibs. 


ft. 
sq. 


ft. 


Total    540  Ibs. 


Performance 

Speed  —  Maximum — Horizontal  Flight  75  miles  per  hour 
Speed  —  Minimum—  Horizontal  Flight  *5  miles  per  hour 
Climbing  Speed  3000  feet  in  10  minutes 


Motor 

Model  OX.  H-Cylinder,  Ve«-,  Four-Stroke  Cycle. .  Water   cooled 

Horse   Power   (ruled)   at   I  KM)  H.   P.   M 90 

Weight  per  rated   Morse  Power  4.33  Ibs. 

Bon-  and  Stroke   4   In.  x  5  in. 

Fuel    Consumption    Hour    9  gals. 

Fuel  Tank  Capacity    21   gajg. 

Oil    Capacity    Provided       Crankcase    4  gals. 

Fuel  Consumption   per   Brake   Horse   Power  per 

Hour     0.60  Ibs. 

Oil   Consumption    per    Brake    Horse    Power   per 

Hour     0.030  Ibs. 

Propeller 

Material      Wood 

Pitch  —  according  to   requirements  of  performance. 
Diameter  —  according  to   requirements   of  performance. 
Direction  of  Rotation  (viewed  from  pilot's  seat)  Clockwise 

Details 

One  Gasoline  Tank  located  in  fuselage. 

Tail  Skid  independent  of  Tail  Post. 

Landing  Gear  Wheel,  size  36-in.  \  t  in. 

Standard  Equipment  —  Tachometer,  oil  gauge,  gasoline  gauge. 

Maximum  Range 
At  economic  speed,  about  250  miles. 


DEHAVILLAND  4 

4OO  HP    LIBERTY 

RECONNAISSANCE  PLANE 


Sc»lo  y  Feet 


88 


SIXGI.K  MOTOHK1)  A  KKOI'I.A  M. 


.ITU -motored  I)t-  I  l.ivili.ind  four,  with  l)oinl)  racks  filled  for  IxHuliing  demonstration 


The  De  Havilland   4  Tractor  Biplane 


The  De  Havill.ind  I  with  the  Liberty  engine  has  been 
one  of  tin-  successful  associations  with  America's  air  pro- 
gram. For  reconnaissance  and  bombing  the  British  have 
i  ill.  I>.  ilavillanil  I-  with  a  Sou  h.j).  Rolls-Royce  en- 
gine, mid  tin-  adoption  of  tin-  Liberty  12  has  given  the 
t  iiitnl  Stat.-s  superior  results  in  both  performance  and 
production. 

With  slight  modifications  in  its  equipment,  the  De  Havil- 
l.-inil  t  is  used  for  reconnaissance,  bomb  dropping  and 
tinhting.  Complete  night  flying  equipment  is  installed, 
consisting  of  .jrceii  and  red  port  and  starboard  electric 
lights  near  the  ends  of  the  lower  plane,  a  rear  white  light 
on  the  deck  just  aft  of  the  gunner's  ring,  and  wing  tip 
Han  lights  near  the  wing  tip  skids. 

Current  for  lighting  and  wireless  is  supplied  by  two 
generators  attached  to  the  inner  sides  of  front  landing 
gear  struts.  A  camera  is  clamped  to  a  padded  rock  on 
the  interior  of  the  body  aft  of  the  gunner's  ring,  where  it 
i-.  coineniently  operated  by  the  observer.  Dual  control 
is  installed,  and  control  stick  is  quickly  detached  and 
removed  by  pressing  a  spring  catch  when  it  is  not  neces- 
sary for  the  observer  to  take  control. 

Hacks  are  provided  for  twelve  bombs  which  are  held 
in  place  horizontally  under  the  lower  planes,  near  the 
body.  The  release  is  accomplished  from  the  pilot's  cock- 
pit by  means  of  bowden  cable.  A  sighting  arrangement 
is  built  into  the  body  just  behind  the  rudder  bnr. 

Four  machine  guns  are  installed.  Two  fixed  Browning 
guns  are  mounted  on  the  cowling  forward  of  the  pilot, 
operated  by  the  "  C.  C."  automatic  interrupter  gear  or 
the  Nelson  direct  mechanism,  which  releases  the  trigger 
at  each  revolution  of  the  engine  crankshaft.  Two  mov- 
alile  Lewis  guns  are  carried  on  a  rotatable  scarfed  ring 
surrounding  the  rear  cockpit. 

A  telescopic  sight  is  provided  for  the  two  fixed  forward 
guns  and  a  ring  and  bead  sight  for  the  twin  Lewis  guns. 

Instruments  carried  are:  Two  gasoline  pressure  indi- 
cators, speed  indicator,  tachometer,  altimeter,  thermometer, 


clock,  hand-pressure  pump,  inclinometer,  map  board,  and 
compass. 

General  Dimensions 

Put 

Span,  upper  plnnr   4.'  t 

Spun,   lower    plane    4iJ3 

( 'liord,  lK>th  planes   4.*7 

Gap  between  planes  8.0 

Staffer     li.6 

Lrnirth  over  all    29.7 

Height  over  all   10.84 

Areas 

Sijuart  fftt 

t'pper    plane    916 

Ix)wer  plane   30i 

Ailerons   (3  upper  and  1  lower)    76 

Totiil  wing  area  with  ailerons   4il 

Stnliiliwr     33.7 

Elevator     833 

Fin     4.1 

Rudder     U.4 

Weights,  General 

Pound* 

Murhine   empty    2,**0 

Ftn-1  and  oil    .' *4i 

Military    load    »** 

Total,   machine   loaded    3,7*0 

Kstiin.il.il    n-cful   load    1,300 

Weights,  Machine  Empty 

Pound* 

Engine    «*» 

Kxhaust  pipes    

Radiator  and  water   1™ 

Propeller      

Gasoline  tanks    

Oil    tank     

Engine   accessories,  leads  etc.    . . . 

Fuselage   with  cowl    3"** 

Tail  plane,  Incidence  gear   

Body  accessories,  seats,  etc 

l'nd"ercarri»(re      ' " 


90 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Front   view  of  the  De  Havilland-4  with  a  400  h.p.   Liberty   "12"   Engine 


Tail  skid    

Controls      

Wings       . . 

Bracing      

Armament    supports 


11 

21 

460 

68 

88 


Total 2,440 


Military  Load 


Crew     

Pounds 
330 

Armament      

163 

Bombs  and  gears   

322 

Photographic   outfit    

22 

11 

Total 

848 

Main  Planes 

There  is  no  sweepback,  but  upper  and  lower  planes  are 
attached  to  a  center  section  and  the  body,  respectively,  at 
a  dihedral  angle  of  174°.  

Aspect  ratio  of  both  planes,  7.7.  Angle  of  incidence, 
3°. 

Fuselage 

Veneer  is  used  for  covering  the  fuselage  from  the  ra- 
diator to  the  gunner's  cockpit,  and  no  diagonal  bracing  is 
therefore  employed  in  this  part. 

The  rear  end  of  the  body  is  constructed  in  the  usual 
girder  fashion,  and  the  longerons,  of  spruce,  are  spliced. 
Veneer  is  used  underneath  the  tail  plane  for  covering  the 
body. 

Tail  Plane 

Attachment  of  the  tail  plane  is  such  that  its  inclination 
can  be  varied  from  the  pilot's  cockpit  during  flight.  Its 
front  edge  is  hinged  and  the  rear  end  braced  by  wires  at- 


tached  to  a  vertical  post  in  the  fin.  By  means  of  a  cable 
wrapped  around  a  drum  and  worm  at  the  lower  end  of  the 
post  the  rear  brace  wires  are  raised  or  lowered,  and  the 
trailing  edge  of  the  stabilizer  is  correspondingly  raised  or 
lowered,  permitting  the  setting  to  be  adjustable  within  the 
limits  of  — 2°  +  5°. 

Engine  Group 

The  engine  is  a  twelve-cylinder  Liberty  which  develops 
400  h.p.  at  1,625  r.p.m.  Bore  and  stroke  5  by  7  inches. 
Cylinders  are  set  at  a  45°  V. 

Zenith  carburetor  and  Delco  ignition  are  used. 

Fuel  consumption  .54  }bs.,  and  oil  .03  Ibs.  pr  h.p.  per 
hour.  Fuel  tanks  are  located  at  the  center  of  gravity. 
Capacity  67.6  gallons.  Oil  tanks  under  pilot's  seat  have 
a  capacity  of  5.6  gallons. 

The  radiator  is  provided  with  shutters  operated  from 
the  pilot's  cockpit,  to  cut  off  part  of  the  cooling  surface 
when  flying  at  low  temperature. 

Propeller,  8.6  ft.  diameter  and  10.7  ft.  pitch.  When 
at  rest  on  the  ground  the  propeller  hub  is  6  ft.  0  in.  above 
ground,  and  in  flying  position  it  is  5  ft.  0  in.  above  ground. 


Performances  Obtained  by  U.  S.  Army  with  the  DeH-4 

Endurance  at  6..300  ft.,  full  throttle  2  hrs.  13  min. 

Endurance  at  6,500  ft.,  half  throttle  3  hrs.     3  min. 

Ceiling    19,500  ft. 

Climb  to  10,000  ft 14  min. 

Speed  at  ground  level   124.7  m.p.h. 

Speed  at  6,500  ft 120     m.p.h. 

Speed  at  10,000  ft 117      m.p.h. 

Speed  at  15,000  ft 113     m.p.h. 

Weight,  bare  plane   2,391  Ibs. 

Weight,   loaded    3,582  Ibs. 


K   .MOTOKKl)   AKMOI'1.. \\KS 


Th,    MrilM,    Vfchei.  ,,,,n,,,,.r,ial    I,  ,,,   •  VJM.J  -  equipped   with  two    HolK-Km,-,    :<75    h.p.    „,,!„,...     Two 

.«-kpit  placeil  high  in  II,.-  MUM-  „„<!  thr  i-Hhin  l«i>  a  sr«tinK  raparily   f.»r  10 
passengers  in  .s«-pHr«tc  .inn  rhiiir-.     Knrl  is  rnrried  for 
five  hours;  speed,  110  m.p.h. 


are  rarrinl    in    Ihr 


The  British  Bristol  Coup*  biplane  equipped  with  ^64  h.p.  Rolls-Royce  engine 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Line  drawings  of  the  D.  H.  5  pursuit  biplane 


SINGI.K   MOTOHKI)   A  KI«)1M.A\KS 


i.-mll,.ii.l    ',.  ,i,,,u,,,..   tl.r   ,-,.,,,li;,r  st,,Btri.r  ,,f  ,)„-   „,,,„.,.  .lrn,Ml  „,,;,.,,   f;vt.s  „„.  Jli|ot  „  widc  rangr  of  vjs|(in 

The  D.  H.  5  Pursuit  Biplane 

This   in  u  liin.    is  a   tractor  biplan.    with   a   single   pair  Chord,  I.S7.1}  m. 

of  iiit<T|iI:nif  struts  mi  each  side  and  with  the  wings  set  Dihrdral,  17'.' 

:it  .-i  n.  ptin    il  tgf  r     t      .;;..',  m.     The  principal  dimen-  Angh-  of  incidrn.-,-.  upper  wing,  2°,  amidwings,  2l/,°  at 

lions,  etc.,  .in  ,s  foll«,«,  tip.  lower  wing  2l//.o  throughout. 

No  .swcfpback. 

Wing  spars  of  spruce  and  of  I-section. 
'  m-  Rihs  spaced  280  to  350  mm.  apart. 


Dimensions  in  millimrters.     Detail  drawings  of  the  D.  H.  5  fuselage 


TKXTHOOK  OF  APPLIED   AKKONAl'TIC  ENGINEERING 


The   IV   Ha\illuml   No.  .>.  Mils;!.'  M-ator  tighter 


The  De  Havilland  No.  5 

Ordinary  four-longitudinal  typo,  braced  by  cross  wir- 
ing and  strengthened  in  front,  up  to  pilot's  seat,  and  at 
rear  near  tail  by  ,S  mm.  plywood.  Body  faired  to  approx- 
imately circular  section  near  front. 

The  undercarriage  is  of  V-type  with  solid  streamlined 
wooden  struts  and  a  continuous  axle.  The  tail  plane  is 
of  one  piece  mounted  at  1°  incidence,  without  the  cus- 
tomary incidence-change  gear. 

The  power  plant  consists  of  a  110  h.p.  rotary  Le  Rhone, 
with  main  fuel  tank  for  100  lit.  of  gasoline  and  oil  tank 
capacity  of  21  lit.  There  is  an  emergency  gravity  fuel 
tank  of  26  lit.  capacity  on  upper  starboard  wing.  The 


engine  is  fed  from  m.-iin  tank  by  compressed  air  generated 
by  small  air  pump.  Total  fuel  supply  for  two  hours' 
flight. 

The  following  instruments  are  mounted  in  the  pilot 
cockpit:  To  right,  two  fuel  supply  pipes  with  stop  cock-. 
and  a  change  of  gear  for  elevator  control:  on  instrument 
board,  tachometer,  speedometer,  altimeter,  -.park  switch, 
watch  and  compass;  to  left,  fuel  and  oil  throttles  and  a 
hand  pump  for  the  air. 

The  weight  of  the  machine  is:  Empty.  U>1  kg.,  and 
fully  loaded.  691  kg.  Wing  area  is  20.1-1  MJ.  m..  wing 
loading  S-H  kg.  sq.  m.  and  power  loading  ."'.;*, •>  kg.  h.p. 


The  Thomas-Morse  S-V  K  Single 
Seater  Advanced  Training  Scout, 
which  makes  a  spwd  of  11.'  m.p.h. 
with  an  SO  h.p.  Le  Rhone  engine 


SIM. I  I.   MOTUKK1)   AKKOl'l    \\l  - 


The  Dayton- Wright  D-4K.     It  has  two  uphol-tcrrd  scats,  huilt-in  mahogany   vanity  ami   lunrh  boxrs,  and  »x-vel  platr  mirror-;.     It 
i<l  pilot.     It  U  equipped  with  a  Lihrrtv  Twelve.     The  machine  has  a  maximum  speed  of  ir.  mil.  ~  |.rr 


holds  two  passengers  anil  |>il<it.     It  is  equipped 
hour  and  minimum  of  53.     The  climb  is  about  10,000  feet  in  10  minutes  and  the 
;  are  similar  to  the  DH-i 


radius  is  four  hours.    The  dimen- 


96 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Dayton-Wright  "  Messenger"  Biplane.     It  has  a  wing  spread  of  18  feet  5  inches,  weighs  4T(i  pounds  net,  636  gross,  has  a  max 
mum  speed  of  78  miles  per  hour,  minimum  40  miles,  and  is  equipped  with  a  37  horsepower 

The  T-4  Messenger 


The  "  Messenger  "  was  designed  as  a  war  machine,  but 
after  being  modified  in  small  details  it  makes  an  ideal  ma- 
chine for  commercial  and  sporting  purposes.  As  a  war 
machine  its  use  was  to  have  been  in  carrying  messages 
from  the  front  lines  to  headquarters,  and  in  general  liaison 
work. 

The  machine  is  exceptionally  light,  and  easy  to  fly,  mak- 
ing it  possible  to  make  landings  in  places  that  have  been 
heretofore  unaccessible.  Very  rigid  flying  tests  have  been 
made. 

The  fuselage  has  absolutely  no  metal  fittings  nor  tie 
rods  of  any  sort,  strips  of  veneer  being  used  exclusively 
for  the  bracing. 

As  an  example  of  its  strength,  the  fuselage  was  sup- 
ported at  either  end  while  12  men  stood  at  the  center. 

The  machine  comes  within  the  means  of  the  average 
sportsman,  for  its  cost  is  said  to  be  not  much  over  $2000. 

General  Specifications 
Span,  upper  plane   19  ft.  3  in. 

STHL'CTUKAI,   DETAILS   OF   THE   D 


9  in. 
17  ft.  6  in. 
6  ft.  1  in. 
6? 
3° 
i/2  in. 


Span,   lower  plane    ' 9 

Chord,   both   planes    :i  *'*•  :Wu  '"• 

Area,  upper  plane   ^°  scl-  "• 

Area,  lower  plane    j6  S1-  ^- 

Gap    • 3  ft.  8>/?  in. 

Stagger     

Length    

Height     

Angle  of  incidence   

Dihedral  of  lower  plane   

Stabilizer  incidence    

Weight   unloaded    4T(i  11)s 

Weight   loaded    

Horizontal  maximum  speed   85  m.p.h. 

Landing    speed     :?T  m.p.h. 

Climb  in  10  minutes   

Engine,  air-cooled  De  Palma    :!T  "-P- 

The  engine  is  a  4-cylinder  air-cooled  "  V  "  type  manu- 
factured by  the  De  Palma  Engine  Company  of  Detroit. 
Its  weight  is  3.7  Ibs.  per  h.p.  The  engine  consumes  4 
gallons  of  gasoline  per  hour  and  tank  has  a  capacity  o) 
12  gallons.  Oil  is  carried  in  the  crankcase. 

AYTOX-WRIGHT  T-4  "MESSENGER" 


I  —  Lower  right  wing  strut  socket,  showing  pulley  for  aileron  cable  fitted  into  the  leading  edge  of  the  wing.  2  —  The  strip  veneer 
used  for  cross  bracing  on  the  interior  of  the  fuselage.  3  —  Attachment  of  upper  wing  section  to  the  center  section.  4  —  Ele- 
vator control  lever.  5  —  Landing  chassis  fitting  snowing  the  streamline  aluminum  casing  for  the  shock  absorber  cord. 


BEQCKMAN5 

IOO  HP   G.V  CNOMt 

SPEED   SCOUT 


3c»U  of  F.,l 


McL«u«him 


98 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Side  view  of  the  Berckmans  Single  Sealer, 
equipped  with  a  Gnome  motor  of 
100  h.p. 


In  a  great  number  of  points,  the  little  single-seater, 
designed  by  Maurice  Berckmans,  shows  a  marked  advance 
in  scout-building  which  has  resulted  in  some  perform- 
ances worthy  of  note.  This  plane  has  ascended  to  22,000 
feet  and  returned  to  the  eartli  in  twenty-seven  minutes. 
Its  normal  climb  is  1100  feet  per  minute.  These  figures 
were  verified  by  an  altimeter  (indicating  barometer)  and 
two  recording  barographs. 

Quick  climbing  ability  is  but  one  of  the  inherent  features 
of  its  design.  The  streamline  monocoque  body,  the  reduc- 
tion of  exposed  parts  and  the  light  total  weight  have  as- 
sisted in  the  achievement  of  high  speed.  A  judicious  dis- 
tribution of  weights  and  areas,  bringing  the  centers  of 
area,  thrust,  gravity  and  resistance  in  advantageous  posi- 
tions, has  made  the  machine  easy  to  control  and  prompt 
and  precise  in  response  to  control  movements.  These  at- 
tributes, together  with  its  neat  details  and  finish,  make 
this  scout  one  of  the  fine  American  machines  of  this 
type. 


General  Specifications 

Span,  upper  plane   ' 26  ft.  0  in. 

Span,  lower  plane  19  ft.  0  in. 

Chord,  both  planes   4  ft.  11  in. 

Gap     5  ft.  3  in. 

Stagger 17° 

Length  of  machine  overall   18  ft.  0  in. 

Height  of  machine  overall  8  ft.  9  in. 

Net  Weight  —  machine  empty   820  Ibs. 

Gross  weight  —  machine  and  load  1,190  Ibs. 

Useful   load 370  Ibs. 

Engine,  G.  V.  Gnome   100  h.p. 

Speed  range   115-54  m.p.h. 

Climbing  speed    1,100  ft.  per  -min. 

Gliding    angle    8  to  1 

Radius   of  action    2%  hrs. 

Main  Planes 

The  upper  plane  is  in  two  sections  with  a  1°  dihedral; 
lower  plane  in  two  9  ft.  6  in.  sections  with  a  2°  dihedral. 
Angle  of  incidence  of  both  upper  and  lower  planes,  2.1°; 
1.5  at  tips.  Stagger,  17°,  amounting  to  16  inches.  No 
sweepback. 

Area  of  the  upper  plane,  10.6  sq.  ft.;  lower  plane,  77.9 
sq.  ft.  Total  supporting  surface,  184.S  sq.  ft.  Loading, 


The  Berckmans   Speed   Scout 

or  weight  carried  per  square  foot  of  supporting  surface, 
6.4  pounds. 

Wing  curve,  Eiffel  No.  32.  Ribs  have  I/.,  in.  by  8/16  in. 
spruce  battens  and  veneer  webs.  Veneer  is  with  3-ply 
birch-gum-birch,  each  lamination  1/16  in.  thick.  Ribs 
spaced  along  the  wing  10  in.  apart. 

Leading  edge  and  the  forward  main  wing  beam  are  of 
spruce,  and  the  rear  beam  of  ash  (the  ash  being  necessary 
because  of  the  relatively  narrow  depth  of  the  Eiffel  wing 
section  at  the  rear  spar).  The  trailing  edge  of  20  gage 
aluminum  tubing  with  an  outside  diameter  of  %  in. 

Ailerons  on  the  upper  plane  only,  4  ft.  10  in.  in  span 
and  1  ft.  11  in.  deep.  The  half-round  leading  edge  is  set 
into  a  curved  recess  in  the  rear  wing  beam,  leaving  no 
opening  between  these  surfaces. 

Interplane  struts  are  of  spruce,  hollowed  for  lightness. 
The  halves  are  glued  together  with  fiber  crossed  (for 
avoiding  warping)  and  bound  in  three  places  to  keep  them 
firmly  in  place.  Maximum  width,  1^4  in->  maximum 
depth  (at  the  center),  4  in.,  tapering  to  1%  in.  at  the 
ends.  The  front  edge  is  nearly  straight  and  the  rear 
curved  in  a  pronounced  gradual  taper. 

Wiring  between  the  planes  is  with  flexible  stranded 
cable;  flying  wires  doubled  and  bound  together  to  lessen 
resistance.  The  compensating  control  cable,  from  one 
aileron  to  the  other,  is  run  concealed  in  the  upper  plane. 
Inspection  doors  are  located  above  the  pulleys,  where  the 
cable  ends  emerge  and  run  to  the  aileron  king-posts. 


Body 

The  fuselage  is  of  the  monocoque  type,  with  a  finely 
tapered  streamline  form.  Its  section  at  all  points  is  per- 
fectly circular;  at  the  forward  end  it  is  3  ft.  0  in.  in 
diameter.  It  is  built  up  of  3-ply  spruce,  except  the  por- 
tion from  the  pilot's  seat  to  the  engine,  which  is  4-ply. 
Laminations  are  1/16  in.  thick,  with  coarse  1/16  in. 
mesh  fabric  interposed  to  keep  the  glue  from  shearing. 

A  headrest  and  streamline  former  is  built  onto  the  fuse- 
lage top  aft  of  the  cockpit. 

At  the  points  where  landing-gear  struts  and  interplane 
flying  cables  are  attached,  the  body  is  braced  with  rings 


SlN(;i.K    MOTOKKI)   AKUOl'I.AM.s 


M 


of  1/1(5  in.  thick   I'   chaniK  1   steel,  meted   to   tin-   int.-rior 
wnll. 

MI.  l»  control  is  installed:  the  stick  for  loBgftndiaa]  nnti 

1-iteral  inn\  i  MK -iits.  :iiul  tlic  foot -li.-ir   fur  ilircrtinn. 

Tail  Group 

I.ijj!.1  -  •  1  tubing  is  used  in  tin  empen- 

nage construction. 

Tlic  tixed  tail  plane  is  srt  at  a  neutral  anijlc.  It  is  in 
two  halves,  attached  to  cither  si<l<-  of  tin-  ln«ly.  Overall 
sjiaii.  •  It.  '.'  in.  :  maximum  depth.  I  ft.  l»  in. ;  ari-a.  s  -i\.  ft. 

Tail  Mips  have  a  span  nt  7  ft.  !»  ill.  and  a  depth  of  1  ft. 
!»  in.;  ana.  !'..'•  M|.  ft.  They  art  n  .  i  ssed  into  tin-  tail 
plain-  so  as  to  leave  no  spai-i-  between  tin-  surfaces. 

Tin  triangular  vi -rtiral  tin  is  I  It.  !i  in.  long  and  1  ft. 
:i  in.  high.  Area.  •_'.."•  sij.  ft. 

Tin-  ruddrr  is  of  tin-  halali.-cd  type,  with  tin-  balancing 
portion  projecting  forward  under  tin-  body.  It  is  ri-ri-ssi-d 
into  tin-  tin  and  liodv  in  the  same  manner  as  the  Haps  and 
tail.  Maximum  height.  .;  ft.  :!  in.;  deptli  re:irw  ard  of  the 
ruddt  r  post.  I  ft.  II  in.;  lialaneed  portion.  7  in.  forward 
of  the  rudder  post.  Hudder  area,  7.5  s<\.  ft. 

Landing  Gear 

(.!••  it  simplicity  is  seen  in  the  lauding  elmssis  construc- 
tion. It  riiiisjstt  of  a  pair  of  '^fi  in.  by  3  in.  Acki-rman 
spring  wheels  attached  to  a  1  '  •_•  ill.  diameter  3  1(5  in.  wall 
tulx  axli -.  Wheel  tread,  5  ft.  3  in. 

Chassis  memlers  are  I1  ,  in.  diameter  14  gage  steel  tube, 
streamlined  with  spruce  fairing  strips.  Cross-wiring  of 
hea\  \  llexilde  cahlf. 

Tin-  tail  skid  is  mounted  on  a  steel  tube  tripod,  and 
.sprung  with  rubber  shock-absorber  elastic  cord. 

Power  Group 

Tin-  engine  is  a  rotary  it-cylinder  General  Vehicle  Com- 
pany's nionosoupape  (uiomc.  Bore,  110  mm.;  stroke,  150 
mm.  Rated  h.p..  100  at  1200  r.p.m.  Weight,  including 
vapori/.er  and  ignition,  272  Ibs.  Fuel  Consumption,  l"i 
gallons  per  hour. 

To  assure  a  good  supply  of  rich  air  to  the  vaporizer 
when  tin-  machine  is  banking  or  spiralling,  and  a  vacuum 
liable  to  occur  on  one  side  of  the  body,  two  intake  ducts 
are  provided,  one  at  either  side  of  the  body. 


Det.nl    view   of   the    Brrrkmans    Scout,    frivinfr   nn    idea   of    tin- 
chassis 


The  propeller  is  8  ft.  4  in.  diameter  with  an  8  ft.  9  in. 
pitch. 

The  cowl  surrounding  the  engine  is  of  1/16  in.  alumi- 
num, reinforced  with  I.  section  aluminum  .-mule  In  .mi.  An 
opening  in  the  side  of  the  cowl  is  made  for  the  exhaust 
of  the  engine,  and  an  opening  at  the  bottom  for  cooling 
the  cylinders  and  to  facilitate  removal. 

Fuel  is  carried  at  either  side  of  the  fuselage  interior  in 
two  Id-gallon  tanks,  running  from  the  engine  bulkhead 
to  the  rear  of  the  cockpit  and  following  the  contour  of  the 
body.  A  7-gallon  oil  tank  is  located  at  the  top  of  the 
fuselage  interior,  just  forward  of  the  instrument  board. 
The  fuel  is  sufficient  for  a  flight  of  v!1  -  hours. 


The  Rrrckmans  Scout     It  is  equipped  with  a  100  h.p.  General  Vehicle  Co.'s  Gnome  engine. 


The  Christmas  "  Bullet "  strutless  and  wireless  biplane  which  makes  a  speed  of  170  miles  an  hour  with  a  6  cylinder  Liberty  Motor 


Details  of  the  fuselage  and  tail  group  of  the  Christmas  "  Bullet "  strutless  scout  biplane 


Front  view   of  the  Christmas  "  Bullet,"   showing  the  absence  of  struts  and  bracing  wires 

100 


Sl.\(;i,K   MOTOKKl)  AKKOIM.ANKS 


101 


I  h,    Christum.,  "  HulU-t,"  in   tli-1,1   at    Mineola.  I..   I. 


The  Christmas   Strutless   Biplane 

>  rnl  ;ittrui|>ts  have  lit  en  made  for  years  by  experi- 
menters to  perfect  .'in  aeroplane  with  flexible  »  in^s.  or 
following  closely  tlic  tli -\iliility  of  tin-  wings  of  a  bird. 
The  biplane  designed  li\  Dr.  \V.  \\' .  Christinas  ap|)<-ars  to 
II.'IM-  met  with  Miiich  success  in  tin-  structure  mentioned, 
and  liis  tlu-orics  of  Hexing  wings  h.-i\e  shown  more  prac- 
ticability than  most  rigid-wing  :idln  rents  were  apt  to  bc- 

lic\e    possible. 

A  most  radical  departiin-  from  what  has  heretofore  been 
believed  to  lie  incessarx  practice  is  the  entire  elimination 
of  struts,  cable*,  and  wires  in  the  bracing  of  the  wings, 
as  well  is  tin  absence  of  wiring  ill  the  internal  structure 
of  the  wings.  The  wing  curve  is  one  developed  by  Dr. 
Christmas,  and  is  of  fairly  deep  section  between  the  main 
wing  beams,  but  tapering  oil'  sharply  aft  of  the  rear  beam, 
anil  merging  into  a  Hat.  thin,  flexible,  trailing  edge.  The 
cH'cct  of  the  section  is  to  maintain  a  high  angle  of  inci- 
is  til--  machine  is  traveling  at  low  speed,  and  a 
lnyli  angle  as  the  machine  gathers  speed,  flattening  out 
the  wing  and  presenting  very  little  resistance. 

I'ppcr  and  lower  wings  have  the  same  aspect  ratio. 
I  pp.  r  wing  has  a  thickness  of  5  inches.  Patents  are 
pending  on  the  wing  construction,  and  full  details  cannot 
now  be  gixcn  of  these  features. 

With    the    wing   section    used.    Dr.    Christmas    has    sue 
<••  <  ded  in  obtaining  a  7-  per  cent,  lift  on  the  upper  wing, 
a  higher  vacuum  than  found  on  any  other  section.      Wings 

set  at  an  incidence  of  .S'.j  degrees. 

\-   the  wings  are  not   braced   transversely,  flexibility   is 

also  obtained  in  that  direction.      I'litl's  of  wind,  or  sudden 

changes  of  direction,  do  not   sharply  afTeet  the  machine's 

•  >r    the   shock    is    transmitted   only    after   being 

ly     alisorlx-d    by    the    resiliency    of    the    wings.       It 

would  seem  that   such  construction  would  result  in  a  low 

factor  of  safety,  but  the  designer  claims  a  safety  factor 

'.•ii   throughout. 

When  at  rest  on  the  ground,  the  wing  droops  in  a  nega- 

tixe  dihedral   of  -  -   7   degrees.      In   flight   the   wing   tips 

i   range  of  flexibility  of  3  feet;  that  is,  the  wings 


can  assume  positixe  or  innatix.  dihedral  measuring  18 
inches  from  the  hori/.ontal  in  cither  direction. 

It  has  I..,,,  demonstrated  Hint  the  wings  carry  a  load 
•O  greater  than  me.  ssjrx  to  sustain  the  machine  in  Hight. 
«nd  this  load  i>  carried  nuardhss  ,,|  wind  pull's  or  extri 
-trains  due  to  increased  wind  pressure  above  or  In-low 
lh  wmn. 

I'he  principal  specifications  of  the  Christmas  "Bullet" 
i"i!ow  s 

•<!•  .in.    II|I|XT   plan.-    .1  |n. 

.-span,   lower   plain-    U   ft.  0  In. 

<  liord,   II|>|MT  plane    i  ft.  (I  in. 

Chord,    lower    plain-    .'  ft.  li   in 

\n-a,    upper    plan.-     140  M].  ft. 

\re.i.    lower    plnnr    30  st\.  ft. 

length   overall    .'1    ft    II  In. 

\\i-itrlit.    in.u-liiiM-    einptx     M.tl  Ids. 

Weiirht.    fully    lonilcd    ." :.loo  llw. 

Miiiiiiiiini   s|M-etl    iO-60  m.ji.li. 

M  ixiiinim    speed    174  tn.pji. 

Cruising    radius     iiO  milr^ 

Oiling    :u,7oo  f|. 

A  Liberty  "  (!  "  is  used,  giving  18.')  h.p.  at  I  KID  r.p.m. : 
the  machine  attains  I7<l  miles  at  three  -quarter  throttle. 
The  weight  fully  loaded  is  with  50  gallons  of  gasoline  and 
5  gallons  of  oil,  sufficient  for  a  sustained  flight  of  three 
hours. 

The  "  Hullet  "  was  originally  designed  as  a  single  sealer 
tighter.  The  pilot  has  an  unobstructed  range  of  vision, 
as  his  eyes  are  at  the  level  of  the  upper  plane  and  the 
lower  plain-  has  such  a  narrow  chord  that  it  offers  but 
\cry  little  obstruction  to  vision.  Although  military  in  . 
sity  docs  not  now  demand  the  adoption  of  the  machine  as 
a  tighter,  it  lends  itself  admirably  to  the  needs  of  civilian 
uses.  The  planes  are  readily  detachable  and  are  easily 
set  up.  as  there  are  no  wires  to  align.  When  the  planes 
are  removed,  they  can  be  stnppcd  alongside  of  the  fuse- 
lage and  the  machine  then  takes  up  only  about  one-fifth 
of  the  room  ordinarily  required  for  storage.  The  machine 
can  be  rigged  up  ready  for  flight  in  15  minutes. 

All  the  controls  are  exceptionally  easy  in  their  opera- 
tion. The  tail  is  flexible,  and  its  efficiency  is  illustrated 
by  the  fact  that  a  1  inch  deflection  causes  a  controlling 
moment  equal  to  that  produced  by  a  rigid  flap  movement 
of  1  inches. 

The  two  main  tail  beams  are  1 '  |.  inches  by  I :t  (  inches 
laminated  spruce.  A  horizontal  V  section  spruce  leading 
•  .Li  is  used.  The  battens  arc  air-seasoned  white  ash. 

Aekerman  spring  wheels  arc  used,  which  cut  down  re- 
sistance and  do  away  with  the  usual  rubber  shock  absorber 
cord. 

The  principle  of  radiation  in  original.  Besides  the  M"-. 
radiator  of  the  "  Livingston  "  ty|>e,  copper  mesh  screens 
cover  in  the  sides  and  top  of  the  fuselage,  forward  of  tin- 
wings,  and  this  surface  has  proven  adequate  for  the  Lib- 
erty "  (i."  Much  of  the  radiation  is  thereby  effected  by- 
skin  friction  rather  than  by  dead  head  resistance. 

The  propeller  has  a  10  ft.  6  in.  pitch  and  in  7  ft.  6  in.  in 
diameter,  designed  for  a  speed  of  195  miles  an  hour,  which 
the  machine  is  expected  to  make  with  full  power. 


102  TEXTBOOK  OF  APPLIED  AEROXAUTIC  EXGIXEERIXG 


LAWSON 

M.T2. 

T  R  ACTOR 


SINGLE   MOTOKKI)  AKHOI'I.AN  I  - 


HIM 


The   Law-son   M.  T.   .'  tractor    biplane 

The  Lawson  M.  T.  2  Tractor  Biplane 


Tin   characteristics  of  tin-  M.  T.  2  nre  Approximately  as 

follow  *  : 


S|.:in.    upper    plain- 
Sp.lll.    low  IT    plane 


;t'l  ff. 

Mi  ft. 

.-,  ft.  J  in. 

5  ft.  1  in. 

8  In. 


tt 

.  upper  plane    (iiicliiiliii)!  ailrroiis)    ...........        >00  si|.  ft. 

.    IIIUIT    plane    ...............................        1.X)   sq.    ft. 

Lrnjrth.  over  nil    .................................  25  ft. 

Hcittlit,  OMT  all    .................................  8  ft. 

-lit.    rmpty     .................................          1,200  His. 

\\.-i_-M.    L.Mlecl 
Speeil    ranj:e 
Clinili.   in    In   minutes 
Clidinjr   anjrlr.   full   load 
Motor.   II  ,11   Scott 


1,900  His. 
4."-90  tn.p.h. 
6.0(X)ft. 
1   in  9 
100  h.p. 


Planes 


Both  wings  are  in  two  sections,  tin-  top  attaching  by 
hiiii-i  •-  to  hinge  ]>lii);s  secured  in  the  cabanc  and  the  lower 
to  plnn-,  secured  to  fittings  and  cross  tit-  tubes  in  the 
fuselage. 

Tin-  spars  are  of  1  section,  having  a  high  factor  of 
>y  (which  incidentally  is  carried  throughout  the  ma- 
rhinc  on  the  more  important  parts).  They  are  left  solid 
at  both  internal  and  external  strut  attaching  points  and 
also  wherever  any  bolts  attach  such  as  for  the  wing  and 
aileron  hinges.  The  ribs  themselves  are  built  of  wood 
webs,  reinforced  with  strips  between  lightening  holes,  and 
cap  strips.  Mahogany  veneer  forms  the  nose  of  the  upper 
surface  of  both  wings  while  false  ribs  are  placed  between 
the  standard  ribs  from  the  entering  edge  to  the  front  spars. 

Between  spars  the  ribs  are  braced  by  stringers  while 
bays  are  separated  by  square  section  struts  channeled  out. 

Double  wiring  takes  all  drift  strains  while  single  is  used 
for  truing  up.  These  wires  are  given  two  heavy  coats  of 
red  lend  while  all  woodwork  is  given  a  coat  of  filler  and  a 
coat  of  varnish. 

Tin-  ir  nlniL'  edge  is  ash,  excepting  at  the  inner  ends  of 

the  wings  and  outer  ends  of  the  ailerons  where  flattened 

1  tubing  is  used.     The  outer  edges  are  of  steamboat 

white  ash  and  slightly  curved  in  plan  view  to  take  the 


tensionnl  pull  of  the  cloth  caused  through  the  contraction 
of  the  wing  dope  upon  its  application. 

Both  wings  are  connected  by  two  pairs  of  interplnnc 
struts  on  each  side  of  the  fuselage.  These  taper  into  cup 
sockets  which  arc  fastened  to  the  wing  strut  plates  by  a 
neat  bolt  and  nut.  The  plates  theniseKes  are  of  the  four 
bolt  type  whereupon  the  bolts  clamp  the  spars  and  are 
prevented  from  sliding  by  blocks  attached  to  the  latter. 

The  lift  cables  arc  all  doubled  and  are  all  of  1/s  cable 
with  the  exception  of  the  main  lift  and  main  landing  wires, 
these  being  .1 

The  ailerons  work  in  conjunction  with  each  other,  being 
interconnected  by  cable  guided  through  neat  fairleads  on 
top  of  the  upper  wing.  Each  is  equipped  with  two  sets 
of  brace  arms  provided  with  shackles  to  take  both  brace 
and  control  cables.  The  control  cables  run  through  pul- 
leys down  to  the  fuselage  where  they  connect  to  a  chain 
and  arc  safetied  to  each  other  as  well. 

Fuselage 

The  longerons  and  vertical  struts  arc  of  straight  grain 
ash  in  front  and  spruce  in  the  rear.  The  longerons  are 
left  solid  their  complete  length,  while  all  struts,  both  ver 
tical  and  horizontal,  have  been  channeled  but  left  solid  at 
all  points  of  connection.  Steel  tubes  fitted  into  sockets 
are  used  for  horizontal  struts  back  to  the  rear  pit  and  also 
to  carry  the  load  from  the  tail  .skid  shock  absorbers. 

Owing  to  the  constant  section  of  both  longerons  and 
struts  in  the  rear  part  of  the  fuselage  the  fittings  are  all 
standard  and  can  be  used  at  any  of  the  stations  in  this 
section.  The  stern  post  is  of  tubing  witli  interchangeable 
fittings  at  upper  and  lower  ends  to  take  the  longerons. 
Each  pit  is  reinforced  with  ash  rims  as  well  as  the  tension 
wires  to  prevent  any  twisting  effect  caused  by  rapid 
manoeuvcring  either  on  the  ground  or  in  the  air,  and  it 
likewise  acts  as  a  protection  in  case  of  a  "  telescoping  " 
landing.  The  whole  fuselage  is  braced  throughout  by 
double  cables  in  the  front  sections  and  wire  in  the  rear. 

The  engine  bed  rails  rest  on  top  of  an  ash  cross-member 
and  are  secured  to  this  by  U-Bolts.  The  whole  unit  is 
braced  by  tubes  fitted  with  plug  ends. 


104 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Gallaudet  E-L  2  Monoplane 

Striking  originality  in  design  is  shown  in  the  twin- 
pusher  monoplane  exhibition  by  the  Gallaudet  Aircraft 
Corporation.  Mr.  Gallaudet's  1919  Sport  Model  has  a 
high  factor  of  safety  and  is  easily  maintained. 

Two  stock  "  Indian  "  motorcycle  engines  are  located  in 
the  nose  of  the  fuselage,  connected  to  a  common  trans- 
verse shaft  and  resting  on  the  top  of  the  plane,  and  driv- 
ing twin  pusher  propellers  on  longitudinal  shafts  driven 
by  bevel  gears. 

Engines  are  "  oversize  "  models,  giving  20  h.p.  each  at 
2400  r.p.m.  Weight,  89  Ibs.  each.  Propellers  are  3 
bladed  (2  bladed  propeller  on  exhibition),  4  ft.  8  in.  in 
diameter  and  7  ft.  0  in.  in  pitch.  Propellers  run  at  one- 
half  engine  speed,  1200  r.p.m. 

The  plane  has  a  span  of  33  ft.  0  in.  and  a  chord  of  4 
ft.  6  in.  Wing  tip  ailerons  are  7  ft.  0  in.  long  and  1  ft. 


0  in.  wide.  Wing  section,  modified  R.A.F.  No.  15.  Di- 
hedral, 178°. 

The  body  is  of  monocoque  construction,  3-ply  spruce 
being  used.  Two  seats  are  provided,  side  by  side,  with 
single  stick  control. 

Tail  areas:  Fin,  2  sq.  ft;  rudder,  4;  stabilizer,  12; 
elevators,  8. 

Overall  length  of  machine,  18  ft.  7  in.  Special  pat- 
ented true  streamline  wires  brace  the  wings.  For  adjust- 
ment and  dissembling  a  rod  from  one  cabane  to  the  other 
permits  slackening  of  the  cables  and  removal  of  planes 
without  loss  of  adjustment.  Turnbuckles  are  therefore 
unnecessary. 

Eight  gallons  of  fuel  are  carried ;  sufficient  for  2  hours. 

With  full  load,  a  speed  of  40-80  m.p.h.  is  attained. 
At  present  the  machine  weighs  750  Ibs.,  but  new  features 
will  permit  a  reduction  in  weight  to  600  Ibs. 


The  small  Gallaudet  twin-motored  monoplane.     It  is  powered  with   two  motorcycle  engines.     Its  size  can  be  estimated  by  com- 
parison with  the  seaplane  above  it. 

The  Gallaudet  E-L  2  "  Chummy  Flyabout  "  Monoplane 


1  —  Formation  of  the  Gallaudet  streamline  cables.  2  —  How  the  upper  part  of  the  landing  wheels  are  fitted  into  the 
monocoque  body.  3  —  Right  hand  shaft  drive  from  the  engines  to  the  pusher  screw.  4  —  Bevel  gear  housing,  connecting  trans- 
verse driving  shaft  with  the  longitudinal  propeller  shaft.  5 —  Attachment  of  bracing  cables  at  the  cabane. 


IE  PEBE  FIGHTER 

400  HP 

LIBERTY  12' MGINE 


i   »   «    '»  •    V   «    «   I 


106 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Side  view  of  the  American- 
built  Le  Pere  Fig'hter,  with 
a  400  h.p.  Liberty  Engine 


The  Le  Pere  Fighter 


Captain  G.  Le  Pere,  an  aeronautical  engineer  in  the 
French  Air  Service,  designed  the  "  La  Pere  Fighter  "  with 
a  Liberty  engine.  It  was  intended  for  use  as  a  fighter  or 
reconnaissance  plane. 

General  Demensions 

Span,  upper  plane    39  ft.  Oy4  in. 

Span,  lower  plane   39  ft.  0>/4   in. 

Chord,  both  planes   5  ft.  6  in. 

Gap  between  planes  5  ft.  0%  in. 

Stagger     3  ft.  01%  in. 

Length  over  all   25  ft.  4%  in. 

Height  over  all   9  ft.  10%  in. 

Weights 

Pounds 

Machine  empty    2,468 

Pilot  and  Gunner   360 

Fuel  and  Oil  475 

Armament     352 


Total     3,655 

Performances  in  U.  S.  Army  Tests 
Height  Speed  Time  of  Climb 

(feet)  (m.p.h.)  (min.  and  sec.) 

0  136  0  min.      0  sec. 

6,000  132  5  min.     35  sec. 

10,000  127  10  min.     35  sec. 

15,000  118  19  min.     15  sec. 

20,000  102  41  min.       0  sec. 

Ceiling,  or  h sight  beyond  which  the  machine  will  not 
climb  100  feet  per  minute,  20,800  feet. 

Main  Planes 
Planes  are  flat  in  span  and  have  no  sweepback.     Top 


plane  is  in  three  sections ;  a  center  section  over  the  body, 
and  two  outer  panels.  Lower  plane  in  two  sections  at- 
tached at  lower  sides  of  fuselage  in  the  usual  manner. 

Upper  and  lower  planes  are  similar  in  shape,  and  with 
ailerons  21%  in-  wide  by  9l!/4  in.  long  attached  to  both. 
An  interconnecting  streamlined  rod  is  used  between  each 
pair  of  ailerons,  located  behind  the  outer  wing  struts. 

Leading  edge  of  upper  plane  is  located  49  9/16  in.  from 
front  of  propeller  hub.  Middle  struts  located  9-1"%  in. 
from  center  of  machine;  outer  struts,  98l/o  in.  from  mid- 
dle struts;  overhang,  41  in.  Interplane  strut  design  is 
unique  inasmuch  as  it  eliminates  the  usual  incidence  wires. 

Fuselage 

Veneer  is  used  for  exterior  finish.  Over  all  length  of 
fuselage,  22  ft.  %  in.  Maximum  section  at  the  gunner's 
cockpit,  32l/>  in.  wide,  45l/o  in.  deep. 

Center  of  gravity  occurs  at  a  point  6  ft.  3  in.  from  nose 
of  fuselage. 

Axle  of  landing  gear  22%  in.  forward  of  center  of 
gravity.  The  landing  gear  wheels  have  a  6~>  9/16  in. 
track  and  are  28  in.  in  diameter. 

Tail  Group 

Over  all  span  of  stabilizer,  98%  in.;  chord,  3 5 1/,  in. 
It  is  fixed  at  a  non-lifting  angle,  and  attached  to  upper 
fuselage  longerons. 

Tail  flaps  or  elevators  measure  ISS1/^  in.  from  tip  to  tip. 
Their  chord  is  31%  in.,  and  in  addition  to  this  there  are 
small  balancing  portions  extending  beyond  the  tail  plane. 

Rudder  is  30  in.  wide  and  has  a  balancing  portion  above 
the  fin,  25  in.  wide. 


Three  quarter  rear  view 
of  the  Le  Pere  Fighter 


SINCil.K   MOTOKKI)   AKHOIM.  \M.S 


KIT 


It    dcXrlops 

in.;  wci-jlit. 
Two    /enilh 


Engine  Group 

\     I    lIl.Tty    "    I'.'   "     II  10    h.p.    engine    IS    lls.d. 

HH»  h.p.  at  \~:>«  r.ji.in.  Horc.  :.  in.;  stroke. 
without  propeller  and  w  it.  r.  s;,.s  pound*. 
Duplex  carburetors  an  us.  d. 

The  radiator  is  lm-.il.il  in  the  ii|i|n  r  pi  nn  center  section. 
anil  its  liN-atiiui  has  in  1-1  ssil.it.  rl  sonir  slight  iiinilitii-.itions 
in  tin-  rnjiini-  to  inrn-.isi  tin  \\ati-r  i-irriilation. 

1'roin-llcr.  !•  ft.  t  in.  in  iliaindi-r.  1  runt  |in)|M.*ller 
pl.-itr  proju-ts  ll:;,  in.  forw.-inl  of  fus,  l.i^,  ,„,,,  . 

I'mpt  Ili-r  .-t\is  I.'.  7  hi  in.  In-low  lop  of  npprr  lonnrroiis. 
In  Hyiiij;  position  tin-  'irop.  lli  r  hull  is  .'.  ft.  ,';s  in.  alnnr 
tin-  unniixi  linr;  \ilnn  it  n-st  on  tin-  Around  tin-  propi-llrr 
hull  is  li  ft.  |::N  in.  aliow  ground. 


Left-  •  h*Ml*.    Tin-  Irti-ion  of  Hi.-  ri-nr  brace  wires  lit 

oirri<-<l  from  mn-  si.l<-  of  UK-  l.in.linjr  ge«r  to  the  other  liy  a  flat 

strel  str.i]i,  f.illnu  injj  nfti-r  (In-   ;i\l.- 
Kijrlit        \ili-roii.     iiitrr-riiiiiiiTtinjr     strut    imil    <i|>rn>ti>ifr     lr\rr, 

sliowinjr  the  means  for  adjiistmrnt  in  UK-  u|»|M-r  end  of  forked 

trrininal. 


Ordnance  Engineering  Scout — 80  LeRhone 

This  m.n-hine  was  tested  at  Wilbur  Wright  l-'ield  by  the 


I'.  S.  A  mix 
Climb  (ft.) 


Summary  of  Results 

Time  Kate       r.p.m.  Speed  r.ji.m. 

o  98  l. l-o 

<>  min.  535          1.1  Hi  9i  l.i;> 

10.000          ]T  min.     :U)  sec.         31 .»         1,100  84  1,175 

15,000         55  min.  1,100  70  1,100 


Service  ceilinfr   13^00  ft. 

U  .-iirht.  empty    s:i",  |b-. 

Total  weijrht  of  load    »i  ll)t. 


Total    weifrfit    1,117  Ibs. 


Ordnance    Scout     with    M    Ix-lthone 


Ordniince    Scout    with    -n    |.,-l(h..n.- 


Ordnance    Scout    with    80    I-elMnm. 


Ordnance    Scout    with    «0 


THE  Of  .C  "«  B 

160  HP   GNOME 

SINGLE  5EATER 


Scale  of  feei 


Mclaughlin 


108 


SI\(;i.K   MOTOHKl)   AKKOIM.ANKS 


I  line  quarter  front   \iew-  of   the  ( ).   I      ( 

Mnjle    Srili-r   Seoul    Itiplalie 


The  O.  E.  C.  Types  B  and  C  Single  Seater 


Tin  type  "  (  "  i-  .in  .•iil.-iiit.-itiun  of  the  Model  "B" 
filthier.  .-UK)  with  tlir  e\re|>tinii  that  the  staggers  differ  iti 
tin-  two  type-  ind  tin-  t.-nik-.  .-mil  weight  distributions  are 

<li(i'rri-iit.  tin    m  in-r.-il  dimensions  of  the  two  types  rem.-iin 
tin-  s.-uii.  . 

Gene'al  Dimensions 

Spun.  II|I|MT  pl:uie   ........................  -'fi  ft.  0  in. 

>p  in.   lower   pl.-ine    ........................  i3  ft.  0  In. 

Chord,    II|>|MT    plum-    ......................  4  ft.  O  in. 

Chord.   IIIM-IT    filiuir    .......................  ;{  ft.  ft  in. 

Cup.  In-twi-fii  pliitK-N    ......................  3ft.  Sin. 

(K.-r.ill    IniL'tli    ...........................  19ft.  0  in. 

Ovrnill   hcijilit    (pn.|x-ll.-r   hiirizimtal)    ......  7  ft.  7  in. 

-•IT     .................................  7  in. 

Areas 


pl.inr 
l.nwrr  pliinr    ..................................      77.H 

Ailrriiiis,  np|«T  pliinr   .........................      175 

Total  wing  area  (with  Hili-nins)    ...............  180. 


Kin 
Huildrr 


3.08 
5.4 


Weights 


Mixlrl  It  .M.Hl,  I  C 

1  1  weight,  full  liuifl   ..............    1^90.  1.090. 

Wright   ]M-r  M|.   ft.  <if   Area    .........  7.15  6.05 

Wright,  pounds  per  h.p  ..............          8.07 


Weights,  useful  Load  —  Model  C 


165 

ll.i-.i-       ........................................     7T 

Tail  Group  ......................................     JS 

l-'nginr     .........................................   *90 

1'roprller     .......................................      i3 

Tanks     .........................................     30 

Winp    ..........................................    150 


Total 


Gaxolinr    ........................................  1*6 

Oil    .............................................  90 

1'ilnt     ...........................................  180 

Fire    Kxtinguisher,  etc  ...........................  16 


Total 


Weight  Distribution 

•  •(  totals) 
Model  It     MiMteiC 

Strurturnl  Weight  ......................  :«.  34.4 

1'ower   I'lant    ...........................  i*3  34.79 

Furl  and  Oil   ...........................  15.5  H.65 

Military  or  f.scful  I.OHC!   ................  i33  18.16 

Performances 
(Climh) 

Time 

Altitude  (minutn) 

(fffl)  Model  B     MixlelC 


5,000    .................................  3J»  8 

10,000    .................................  6.6  17 

15,000    .................................  16.  40 

20,000    .................................  96  A 

Oiling    ...............................  M 


Hear  view  of  the  O.  F..  C.  Type  B 
Gnome  Kngine  Scout 


110 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  O.  E.  C.  80  horse-power  Le  Rhone  training  scout 


13(5 


(Speed) 
Altitude 
(feet) 

0 

5,000 

10,000     

15,000 

20,000 

Ceiling 

Stalling  Speed  51 

(Duration) 

Maximum   ninge,  at   10,000  feet 
Model  B 

At  full  power 

At  minimum  power 


(Miles  per  Hour) 
Model  B       Model  C 


104 
101 
96 
90 
83 
72 
33 


Model  C 
2%  hours 
3  hours 


Main  Planes 

Aspect  ratio  of  upper  wings,  6. 5;  lower  wing,  6.14. 

Safety  factor  of  wing  truss  at  high  speed,  6;  at  low 
speed,  7.  Wings  have  no  sweepback  nor  dihedral.  Deca- 
lage,  1  degree.  Angle  of  upper  wing  to  propeller  axis, 
1.5°;  lower  wing,  0.5°. 

Gap  to  chord  ratio,  0.947. 

Wing  section,  R.  A.  F.  Number  15. 

Clear  vision  is  obtained  forward  through  an  angle  of 
45  degrees  between  wings.  The  only  blind  spots  are 
through  an  angle  of  8  degrees  for  the  top  wing  and  33 
degrees  for  bottom  wing. 

Ailerons  are  6  ft.  9  in.  long  and  1  ft.  7  in.  deep.  Cen- 
ter of  pressure,  9  ft.  6%  in.  to  longitudinal  axis. 

Tail  Group 

Stabilizer  span,  7  ft.  6  in.;  depth,  1  ft.  10  in.  Center 
of  pressure  to  center  of  gravity  of  machine,  11  ft.  10  in. 

Elevators  are  8  ft.  2  in.  in  span;  depth,  2  ft.  0  in.  Cen- 
ter of  pressure  to  center  of  gravity  of  machine,  13  ft.  4  in. 

Rudder,  3  ft.  4  in.  high  and  2  ft.  0  in.  deep.  Center  of 
pressure  to  center  of  gravity  of  machine,  13  ft.  4  in. 

Fin,  1  ft.  8  in.  high,  2  ft.  10  in.  deep.  Center  of  pres- 
sure to  center  of  gravity  of  machine,  11  ft.  9  in. 

Landing  Chassis 

Wheels  have  a  track  of  5  ft.  0  in.  Angle  of  center  of 
gravity  ground  point  and  vertical  13l/>  degrees. 


Chassis  designed  to  stand  up  when  fully  loaded  ma- 
chine is  dropped  from  a  height  of  10  inches. 

Fuselage 

Length  of  fuselage,  15  ft.  11  in.  Maximum  section, 
3  ft.  5  in.  by  3  ft.  5  in. 

Fuselage  designed  to  stand  a  load  of  30  pounds  per 
sq.  ft.  on  horizontal  tail  surface  and  dynamic  loading  of  5. 
Engine  section  has  a  safety  factor  of  10. 

The  instruments  on  the  dashboard  are  as  follows: 
Dixie  Magneto  switch;  Phinney-VValker  rim  wind  clock; 
longitudinal  inclinometer;  horizontal  inclinometer;  Alti- 
meter (20,000  ft.);  Tachometer,  Signal  Corps,  type  B; 
and  a  Sperry  Air  Speed  Indicator.  The  clock,  Altimeter, 
Tachometer,  and  Air  Speed  Indicator  have  Radiolite  dials. 

A  Pyrene  fire  extinguisher  is  conveniently  mounted  at 
the  left  of  the  seat,  connected  so  as  to  be  pumped  directly 
into  carburetor,  or  it  may  be  used  separately. 

Power  Plant 

(LeRhone) 

The  80  h.p.  Le  Rhone  engine  develops  its  rated  h.p.  at 
1200  r.p.m.  Fuel  tanks  are  mounted  between  the  engine 
and  the  pilot,  over  the  center  of  gravity. 

Capacity  of  gasoline  tank,  18  gallons,  Oil,  4  gallons. 
Weight  of  gasoline,  110  Ibs.,  sufficient  for  2*4  hours. 
Weight  of  oil,  28  Ibs.,  sufficient  for  2%  hours.  Gasoline 
consumption,  0.60  pounds  per  b.h.p.  hour.  Oil,  0.13 
pounds. 

Propeller,  8  ft.  41/.  in.  diameter  and  7  ft.  61/-;  in.  in 
pitch. 

Height  of  propeller  axis  above  ground  with  machine 
in  flying  position,  4  ft.  11  in. ;  with  machine  at  rest,  5  ft. 
6  in. 

Power  Plant 

(Gnome) 

The  Gnome  engine  is  of  French  manufacture.  At  1200 
r.p.m.  it  is  rated  at  160  h.p. 

Gasoline  consumption,  .85  pounds  per  h.p.  per  hour; 
Oil,  16  pounds  per  h.p.  per  hour;  Gasoline  capacity,  35 
gallons;  weight  210  pounds.  Oil  capacity,  4  gallons; 
weight,  28  pounds. 


THE     MARTIN 

45  HP     ABC     ENGINE 
KDI      SCOUT 


Scmim  tf  F..I 


Mclaughlin 


111 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Martin 
K-III  Single 
Seater  with  a 
two  cylinder 
Gnat  A.  B.  C. 
engine  devel- 
oping 45  h.p. 


The  Martin  K-III  Single  Seater 


Some  of  the  distinctive  features  of  the  Martin  K-III, 
•15  h.p.,  single-seater,  are  retractable  landing  chassis,  the 
K-bar  cellule  truss,  wing  end  ailerons,  and  shock-absorb- 
ing rudder,  which  have  been  patented  by  Captain  James  V. 
Martin,  the  American  aeronautic  engineer.  These  fea- 
tures are  interesting  solutions  of  difficult  aerodynamical 
and  constructional  problems  and  show  the  tendency  of 
modern  design  toward  the  attainment  of  efficiency  with 
low  power  rather  than  the  employment  of  great  power  to 
overcome  the  disadvantage  of  uncertain  design. 

The  K-III  was  designed  as  an  altitude  fighter,  and  is 
equipped  with  oxygen  tanks  behind  the  pilot's  seat  and 
provision  for  electrically  heating  the  pilot's  clothing.  The 
seat  is  so  located  that  excellent  vision  is  obtained;  vision 
vertical  circle  from  dip  of  ,r>°  dead  ahead  through  an  arc  of 
180°;  horizontal  circle  360°,  transverse  circle  from  dip  of 
27!/2°  through  an  arc  of  235°. 

The  machine  can  light  upon  and  start  from  a  country 
road  and  can  travel  22  miles  on  one  gallon  of  gasoline, 
making  it  an  economical  means  of  carrying  mail  and  light 
express  in  rural  free  delivery,  etc. 

Dimensions 

Span,  upper  plane   (without  ailerons)    15  ft.  0  in. 

Spun,   lower   plane    17  ft.  11%  in. 

Chord,   both   planes    3  ft.  6  in. 

Gap  between  planes   4  ft.  fi  in. 

Length  overall   13  ft.  3'/2  in. 

Height  overall    7  ft.  4%  in. 

Areas  (Sq.  Ft.) 

Upper  plane  (without  ailerons)   53.50 

Lower  plane   47.80 

Ailerons     5.00 

Stabilizer     9.50 

Elevators     6.66 

K  udder     4.88 

Weights  (Lbs.) 

Engine 85.50 

Wings     60.75 

Ailerons   and   supports    9.50 

Chassis  and  retracting  mechanism   16.38 

Wheels    17.50 

Struts,  wires  and  K  bars   8.25 


Oil   and  gasoline  tanks    .................................  9-7;> 

Rudder  and  tail  skid   ...................................  7-75 

Damper   and   elevator    ..................................  14.50 

Fuselage,  complete    .............................. 

Propeller   and   hub    .....................................  13.63 

Total  weight   ....................................  :550-°° 

Performance  (Estimated) 
Altitude  (Ft.)'  Time.(Min.)  Speed  (m.p.h.) 


0 

5,000 
10,000 
15,000- 
20,000 
25,000 


0 

3 

6 

11 

18 

28 


speed    145 


135 
113 

HI 

108 
07 
m.p.h.    at 


10,000 


(With   60   h.p.,    100-lb.    engine 
feet.) 

Endurance  at  10,000  feet: 

At  full   power    .....................   223  miles 

At   minimum    power    ...............   216  miles 

Main  Planes 

The  planes  have  neither  stagger  nor  dihedral. 

The  aerofoil  of  main  planes  is  known  as  the  "  Ofenstein 
1."  At  10  m.p.h.  the  Ofenstein  wing  section  has  a  lift- 
drift  ratio  of  22  to  1. 

Upper  plane  is  in  a  single  continuous  span.  Wing 
ends  are  at  right  angles  to  the  leading  edge,  and  are 
finished  off  with  a  semi-circular  termination  which  varies 
in  radius  as  the  wing  varies  in  thickness.  The  half-round 
wing  ends  are  characteristic  of  all  the  aerofoils  of  the 
Martin  K-III. 

Principal  wing  spars  for  main  planes  are  centered  14l/> 
in.  back  of  leading  edge,  where  the  trusses  carrying  the  lift 
are  direct  instead  of  bridged  between  the  ribs. 

The  front  of  main  wing  beam  is  coincident  with  the 
most  forward  travel  of  the  center  of  pressure. 

The  lower  plane  is  in  two  sections,  and  attachment 
made  to  the  fuselage.  Wing  ends  are  raked  at  an  angle  of 
1  5  degrees. 

Interplane  bracing  is  of  the  "  K-bar  "  cellule  truss  type. 
The  head-resistance  is  reduced  4  per  cent  through  the 
elimination  of  struts  and  wires. 


SINCil.K   MOTORED  .\  KHOIM.ANKS 


113 


1  unit  \  i<  »   ui   tin-  Martin   Kill  Scout, 


l>y  C.i|it.iin  .1  inn  s   \'.  Martin,  -mil  comprising  sonic  of  DM-  special  Martin  feature-. 
The   holding  jrrnr  is   shown   in   it-,   retracted  position 


The  percentage  nf  intfr  i-i  llule  interference  with  the 
•K-bar  truss  is  \S  -is  i-mii]i:iri  >1  with  -'.'•'  '<  in  tin-  standard 
truss;  a  total  reduction  of  Hi' I.  Of  this  reduction.  16% 
is  due  to  tin-  cliniiii.-itiiin  of  struts  and  win-s  while-  -i\''/c,  is 
due  to  the  increased  gap  obtained  without  subsequent 
weakening  of  truss  or  increase  of  structural  resistance. 

K  ^Iruts  centered  1  t  ft.  from  one  another.  The  vertical 
member  is  ^  ft.  .'('^  in.  long;  greatest  section.  I1  t  ill.  by 
I1  ,  in.  The  angular  members  of  K-struts  are  attached  to 
rear  wing  beams  located  18  in.  back  of  main  beams. 
These  members  are  of  steel  tube  faired  with  sheet  aero- 
metal. 

The  vertical  member  of  the  strut  is  not  subject  to  any 
bending  moment  at  the  juncture  of  the  inclined  members, 
for  the  upper  member  is  in  tension  and  the  lower  in  com- 
pression, thereby  neutralizing  the  forces  at  that  point. 
The  mid-strut  fitting  is  designed  with  a  view  to  equalizing 
the  moments  and  relieving  the  vertical  member  of  all 
c\c<  pt  the  usual  direct  compression. 

l-'lying  and  landing  wires  are  .3  16  in.  diameter.  Cen- 
ti  r  se.-tion  .TOSS  bracing  is  with  's  in.  diameter  wire. 

Tin-  wing-end  ailerons  are  an  unusual  departure  from 
customarv  aileron  disposition.  They  have  n  righting  influ- 
ence per  square  foot  of  area  of  t  to  1  with  the  added 
advantage  that  they  do  not  impair  the  efficiency  of  the 
aerofoil  to  which  they  are  attached. 

The  ailerons  have  a  symmetrical  double  convex  surface 
and  are  so  balanced  that  their  operation  requires  very  little 
effort 

Ailerons  are  operated  by  means  of  a  sliding  rod  running 
through  the  upper  plane.  Two  cables  running  up  the 
center  panel  struts  cause  the  rod  to  slide  from  side  to  side. 
At  the  wing  ends,  the  bar  fits  into  a  tubular  collar  attached 
to  the  ailerons.  The  collar  is  provided  with  a  spiral  slot 
or  key  way  through  which  a  pin  from  the  rod  projects. 
The  sliding  movement  of  the  rod  causes  a  rotary  move- 
ment of  the  aileron  collar.  This  method  does  away  with 
all  exposed  actuating  meml  <  rs. 


Fuselage 

Overall  length  of  fuselage  from  engine  plate  to  rear 
termination.  1(1  ft.  10  7  1(5  in.  Maximum  depth.  X  ft. 
(H,  in.  (not  including  streamline  head  rest);  maximum 
width.  -.'  ft.  •-!••'*  in. 

The  center  of  gravity  is  located  2  ft.  7 '  i-  in.  back  of  the 
engine  plate. 

Veneer  of  ply-wood  is  used  for  the  internal  construction 
of  the  fuselage. 

In  flying  position,  the  top  of  the  rounded  turtle  deck  is 
practically  horizontal.  The  upper  longeron-,  as  well  as 
the  lower  have  an  upward  sweep  towards  the  rear.  The 
fuselage  terminates  in  a  vertical  knife  edge  18  in.  high. 

Internal  bracing  of  the  fuselage  is  with  solid  wires 
looped  over  clips  at  the  ends  of  cross-bracing  members. 
Wires  are  run  in  series  of  four  each,  grouped  in  ribbon 
form.  Each  wire  has  a  tensile  strength  of  2."it>  Ibs.  each; 
at  the  cross-braces,  they  run  over  a  :<  Hi  in.  radius.  Only 
eight  groups  of  wires  and  eight  turnbuckles  are  required 
in  the  internal  bracing  system. 

The  cowling  and  propeller  spinner  are  of  "  aeromet.il. 
having  the  tensile  strength  of  sheet  steel  at  one-third  of 
the  weight  of  steel. 

Where  engine  cylinders  project  from  the  body,  half- 
conical  formers  carry  out  a  streamline. 

The  fuselage  is  designed  to  stand  a  load  of  I  OS  Ibs.  per 
sq.  ft.  of  horizontal  tail  surface.  Factor  of  safety,  six. 

Instruments  carried  are:  Altimeter,  tachometer,  gaso- 
line gage  and  oil  gage. 

Tail  Group 

The  horizontal  stabilizer  has  a  span  of  7  ft.  6  in.  and 
width  of  2  ft.  (>  in.  Ends  are  raked  at  a  15°  angle. 

The  stabilizer  is  located  in  line  with  the  center  of 
thrust.  It  is  fixed  at  a  non-lifting  angle  and  supported 
from  below  by  a  pair  of  steel  tube  braces. 

Elevators  are  12  in.  wide  and  have  an  overall  span  of 


114 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Engine  mounting,  Martin   K-III 


Three-quarter    re;ir    view    of    the    Martin 
K-III   fuselage 


7  ft.  10  in.  For  rudder  clearance,  the  inner  ends  of 
elevators  are  raked  30°. 

Rubber  covering  between  stabilizer  and  elevators  closes 
the  gap  between  the  surfaces,  giving  a  smooth,  unbroken 
outline. 

There  is  no  fin. 

The  rudder  is  provided  with  balanced  areas  above  and 
below  the  fuselage. 

The  tail  skid  is  contained  within  the  rudder.  It  is  pro- 
vided with  rubber  elastic  shock-absorbing  cord  similar  to 
the  customary  practice.  It  is  especially  effective  when 
taxying  on  the  ground.  The  combining  of  the  rudder 
and  tail  skid  does. away  with  considerable  weight  and  air 
resistance  while  adding  to  the  effectiveness  and  simplicity 
of  the  construction. 

The  rudder  is  1  ft.  10  in.  wide;  maximum  height,  3  ft. 
5  in.;  balanced  portions  project  8  in.  forward  of  the  prin- 
cipal rudder  area. 

Flexible  3/32  in.  cable  is  used  for  operating  the  rudder, 
by  means  of  the  usual  foot  bar. 

The  elevators  are  actuated  by  means  of  a  single  %  in., 
20-gauge  steel  tube  from  the  control  stick  to  a  lever  pro- 
jecting downward  from  the  center  of  member  forming  the 
elevator  leading  edge.  The  fuselage  terminates  beyond 
the  elevator  leading  edge,  providing  space  for  the  enclos- 
ure 'of  the  operating  lever. 


Landing  Gear 

Ackerman  spring  wheels  are  used  for  the  landing  gear; 
these  have  2  in.  tires,  and  are  20  in.  in  diameter.  The 
two  wheels  weigh  171/'  ^)s-  Wheel  track,  2  ft.  5  in. 
When  the  chassis  is  extended,  the  underside  of  the  fuselage 
at  the  forward  end  is  raised  2  ft.  3  in.  above  the  ground. 
When  drawn  up  during  flight,  only  the  wheels  are  exposed. 

The  front  of  axle  and  the  two  forward  struts  have  flat 
front  faces,  so  that  when  in  flying  position,  these  members 
fit  flush  into  the  fuselage  bottom. 

A  hand-operated  worm  gear,  operated  during  flight, 
causes  the  chassis  to  be  retracted  with  practically  no 
effort  on  the  part  of  the  pilot. 

The  landing  gear  has  a  factor  of  safety  of  20. 

Engine  Group 

The  power  plant  consists  of  an  air-cooled  two-cylinder 
opposed  "  Gnat  "  A.  B.  C.  engine,  developing  45  h.p.  at 
1950  r.p.m. 

Fuel  consumption,  .56  Ibs.  per  h.p.  per  hour ;  weight, 
50.4  Ibs.  Oil  consumption,  .017  Ibs.  per  h.p.  per  hour; 
weight,  1.55  Ibs. 

The  fuel  tank  is  located  in  the  upper  main  plane  above 
the  fuselage.  It  has  a  capacity  of  9.03  gallons,  sufficient 
for  a  flight  of  two  hours. 


SIX(iI.K   MOTOKKl)  AKKOIM.. \.\KS 


II.-) 


.ni      Itipl.ini-,     wilh      -peri  i!     - 
cilinilcr    I'.i.k.ird    a\i.ili<m 


The  Packard  Aeroplane 


Tin-  I'.-ickard  two  plan-  tractor  was  ili-sim,,.,!  around  and 
in  nli-  i  complete  unit  with  tin-  Model  1-A-TU  Packard 
.\\iation  r'.iipnc  This  in.-ii-liiiii-  will  make  about  loo 
m.p.li.  with  full  lo.-id.  on  .-u-coniit  of  its  li^ht  weight  and 
i  li -.-in-i-iit  design,  .-mil  \-i-t  its  landing  S|H-K|  is  as  low  as  the 
:I\IT:II;I-  training  aeroplane. 

I  1-1  cms*  rniuitry  trips  ;in  in  nli-  possible  in  (lijs  .ship, 
with  tin  ability  to  land  in  relatively  small  fit-Ids.  Tin- 
uriii  ral  spri-iticatinns  are  as  follows: 

Power  Plant 

r.-n-k.-ird  s  (vliiulcr  KiO  h.p.  at  l.)4."i  r.p.m.  \V(-ij;lit. 
riiinplrtr  with  huh,  startrr.  battery  and  engine  water,  :>H.~, 
li>s.  I  in-1  consumption.  ..',0  to  .,U  ll>s.  per  h.p.  hour  at 
sea  level. 


Weights,  Areas,  etc. 


AreH,  main   plam-s    387  «q.  ft. 

Wright,   innehinr  <-in|ity    .  I^.Hl  Ills. 

Normal   flying   wi-ijjlit  ' .'.Hi;   Ills. 

\\'ri)rlit.  Ihs.   |«-r  h.p l:«..i  His. 

Winfr  lomliiijr,  p<-r  sq.  ft .i.i>  M"«. 

IVniiU~il.il-   i-\tra    luggage    HXI  Ihs. 


Altitmli- 


Performance  (Estimated) 

Tim,  of  Climb 
(ininulc- ) 


Spi-i-il 
(m.p.h.) 


101 

100.5 
9« 

15,000  (>o> 

Absolute  ceiling,  19,500  feet. 


34.5 


I-  ui-l  rmifre 
(hrs.) 

:< 
U 

4 


SO.MK    DI-.TAII.S   OK   TIIK    I'\(K\HI)   T\V(>   SKVIT.lt    Tit  ACTOR 


I — Tlx-  shiM-k  alisorlx-r  arninp-mrnt.     Thf  axle  is  sqniirr,  where  it    run*   in   the  chassis   slot.     The  elastic  conl    is  iliviili-d    into  two 
(rron|is.  one  fore  nml  one  nft  of  the  nxle.     i?  —  The   roomy   suit    ras(-    Iwker   coinpnrtment    Ix-himl    the    pilot's    seat.     A    i, 

with  ilov.-taiU-o1  nlgrs  tits  IIMT  tin-  op<-nin(f.     '.I       Donlih-  stilling  cover  plates  an-  ns.-il  to  |>rrmit  r«sy  access  to  the  unih-r 
•>f  tlx-  engine  in  the  vicinity  of  the  air  intake,  projecting  through  the  fnsrlnjn-  Uittoin.     4       Wing  construction.     Webs  are 
of  thin  mali,ii:.iii\    vi-ni-er.     Cap  strips  anil  triangular  section  |i-ailing  edge  of  spruce.     Short  false  rihs  run  from  leading  edge  to 
main  front  heam.     5  —  Tail  skid  and  anchor  plate  for  stabilizer  braces 


THE  '5TANDA&D'  M 

GNOME  OR  LERHONE  ENGINE 

SECONDLY  TWINING  PLANE 


of  /eel 


23*5 


116 


SIXC1.K   MOTOKK1)  .\KKO1M..\\KS 


117 


Hi.    Standard  Model   K-l   Sing 


"II    ll  |>.     I    I-     Kllollr    rll^ilir. 


The  Standard   E-l    Single  Seater 


Height 

(l-Vet) 
8,500 

10.000 


Summary  of   Performances   (Continued) 
(With  1..-  Hhone  Kngine) 


Time  of 
(limb 

Hi  min.    30  s.v. 
-'->  min.     30  sec. 


II at.- of  Climb 
Kt.  |MT  mill. 

900 


Speed 

(m.p.h.) 

90 

85 

(Viling,  14,500  feet. 
Stalling  speed,  48  m.p.h. 
(Hiding  angle,  1:7. 
Maximum  range:     At  5,000  ft.,  iOO  miles;  10,000  ft.,  160  mites. 


Tin  "  K  I  "  Single  Si.-itir  was  designed  ;is  :,  si-condary 
training  machine.  It  is  provided  with  either  an  80  h.p. 
I  (  Itlione  or  a  101  h.p.  Gnome  engine,  but  in  either  case 
the  dimensions  of  the  machine  remain  Ihe  same. 

Tin-  It.  A.  I'.  No.  I  .'P  wing  curve  is  used.  Dihedral.  Xr/i  : 
aspect  ratio  of  both  planes.  7;  stagger,  13.02  in.  There  is 
no  sweepliack  nor  decalagc.  Wings  are  set  at  an  angle 
of  2°  to  the  propeller  axis. 

Maximum    diameter    of    fuselage,     K''-j    in.;    fineness 

General  Dimensions 
Power  Plant  Feet 

(Lf  Rhone)  sl'"n-  "PP"  P'am>   ** 

Span,  lower   plane    94 

Tin-   I..-  Khonc  is  a  nine-cylinder,  air-cooled  rotary  en-  Chord,  both  planes    3.5 

gine  developing  80  h.p.  at  120O  r.p.m.  and  8  I  h.p.  at  1290.  Gap   between   planes 4 

More  and  stroke.  M     Mi  in.  by  .1 '  ..  in.  length  over  all   ...18.85 

I'll,  I  tank  located  near  center  o*f  gravity,  has  a  capacity 

of  20  gallons.      Fuel  is  consumed  at  the  rate  of  .725  Ibs.  . 

P-T  h.p.   per  hour.  Square  feet 

Oil  tank,  located  below   fuel  lank,  has  a  capacity  of  3  t'pper   plane    81 

gallons.     Oil  is  consumed  at  the  rate  of  .03  Ibs.  per  h.p.  Ix>wer   plane    7J.:» 

per   hour  Ailerons   (J  upper  and  J  lower)    93.2 

Total  wing  area  with  ailerons   1533 

(Gnome)  Stabiliser    19 

The  nine-cylinder  rotary  Gnome,  manufactured  bv  the  *  levator     19.7 

"  *  I** in  -J  fl 

General    Vehicle    Company,    is    known    as    tv|>e    B-2.      At  .. 
I  -i'ii  r.p.m.  it  delivers  KM  h.p.      Bore  and  stroke,  110  mm. 

by  l.'.d  mm.  Summation  of  Weights 

Fuel  tank  has  a  capacity  of  29.5  gallons;  rate  of  con-  (With  !.<•  Ithonc  Kngine) 

sumption.  .81)  Ibs.  (>cr  h.p.  per  hour.  Wright  in         Percentageof 

Oil  tank  capacity,  5  gallons;  rate  of  consumption.  .20  pounds           gross  weight 

,.                                                                                                                           Power    plant    434  36.4 

Ibs.  per  h.p.  per  hour.                                                                            K,,,  I  ami  oil  140  11.8 

Pilot  and  miscellaneous  equipment. ...     179  15.1 

Summary  of  Performances                                     Armament     98  9.4 

(With  I-e  Hhone  Kngine)                                           llody    structure 141  11.9 

Height                 Speed                         Time  of                Rate  of  Climb        Tail  surfaces  with  bracing   36  3.1 

(Keet)                (m.p.h.)                        Climb                    Kt.  per  min.          Wing  structure    156  13.1 

Ground              100-103                   0  min.       0  sec.                 705                     Chassis      74  6.9 

5,000  8  min.       0  see.  705 

-..-."o                         95                                                                                                   Total      1.188  100.0 


118  TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  VE-7  Training  Biplane 


The  VE-7  machine  is  designed  around  the  1  50  h.p.  His- 
pano-Suiza  8-cylinder  aeronautical  motor,  driving  a  direct 
connected  two-bladed  tractor  air-screw.  The  entire 
power-plant  unit,  with  all  accessories,  is  mounted  in  a 
detachable  forward  section  of  the  fuselage. 

General  Dimensions 

Span,   upper    plmie    34  ft.  4  in. 

Span,  lower   plane 31  ft.  4  in. 

Chord,  both  planes   S  in. 

Gap  between  planes   4  ft.  8  in. 

Stagger    1 1  in. 

Overall    length    24  ft.  5  in. 

Overall  height    8  ft.  8  in. 

Areas  (square  feet) 

Main   planes 297. 

Stabilizer    19. 

Fin     2.30 

Ailerons    37.42 

Elevators 17.09 

Rudder     7.8 

Main  Planes 

Four  aileron  type,  with  cut-away  top  center  section. 
The  incidence  is  differential. 

No  sweepback.  Dihedral,  1^/4°.  Wings  are  in  five 
units,  assembled  together  with  submerged  hinges.  In- 
ternal lateral  control  mechanism. 

Spars  are  of  selected  spruce,  I-beam  section,  re-enforced 
at  panel  points.  Ribs  are  of  unit  assembly  type,  built  up 
of  spruce  and  ash  battens,  with  poplar  webs,  while  for 
miscellaneous  parts  ash,  birch  and  cedar  are  employed. 

The  internal  bracing  system  utilizes  double  swaged 
wires  and  forked  ends  attached  to  stamped  mild  steel  fit- 
tings anchored  to  the  main  spars  through  neutral  axles. 

Main  plane  fittings  are  submerged  and  the  strut  sockets 
are  designed  flush  to  the  wing  surfaces. 

Wing  frames  are  covered  with  approved  linen,  or  cotton 
fabric,  specification  sewed  to  ribs  and  "  pinked  "  taped. 
Surface  treatment  is  five  coats  of  acetate  dope  and  two 
coats  of  special  grey  enamel. 

Inter-plane  struts  are  of  selected  spruce,  solid  one  piece 
design,  tapered  slightly.  The  strut  section  is  of  very  low 
head-resistance. 

Cellule  bracing  is  Roebling  10-strand  cable,  fitted  with 
Standard  turnbuckles  for  adjusting  means.  Flying  wires 
are  doubled,  landing  wires  single. 


Fuselage 

Carefully  cleaned-up  design  of  extreme  simplicity.  Fit- 
tings incorporate  special  anti-drift  details.  The  frame 
is  a  box  girder  of  steel  and  wood  construction,  unit  type 
except  for  detachable  engine  mounting,  with  trussing  of 
double  swaged  wires. 

Cross-section,  rectangular  but  crowned  top  and  bottom, 
tapering  to  a  vertical  knife  edge  at  the  rear.  Dimensions 
at  maximum  section,  401';.  in.  deep  x  30  in.  wide. 

Motor  housings  and  cowling  are  of  stamped  sheet 
aluminum,  after  portion  being  fabric  covered. 

Cowlings  enamelled  light  blue,  fabric  doped  and  grey 
enamel  finished. 

Large,  lunged  vision  doors  render  motor  parts,  control 
mechanisms  and  tail-skid  system  readily  inspected  and 
accessible. 

Seating 

Two  seats,  in  very  comfortable  tandem  arrangement,  in 
well  protected  and  upholstered  cock-pits.  Front  seat  be- 
tween wings,  well  forward  to  obtain  vision.  Cut  outs  in 
upper  center  section  and  lower  wings  facilitate  vision  from 
rear  seat. 

Exceptional  vision  provided.  Cock-pits  fitted  with  re- 
enforced  windshields. 

Longitudinal  weights  very  close-coupled. 

Empennage 

Composed  of  fixed,  double  cambered  st;ibilizer,  con- 
nected dual  elevator  flaps,  fixed  vertical  fin  and  balanced 
rudder.  All  frames  are  of  steel,  welded  and  brazed  to- 
gether, wood  rib  filled,  over  tubular  steel  and  spruce  spars. 

System  internally  braced  with  swaged  wires  and  car- 
ried externally  by  crossed  cables  and  turnbuckles,  giving 
a  most  rigid  tail  construction  to  withstand  high  stresses  in 
"  stunting." 

Empennage  locked  in  place  to  fuselage  by  a  series  of 
exclusive  design  features. 

Tail  units  covered  with  wing  fabric  and  finished  to 
match.  Doubled  control  wires  connect  up  all  control  sur- 
faces. 

Chassis 

Type  "  V  "  strut  and  dual  wheel  design.  Entire  chassis 
quick  detachable  by  removing  1  hinge  pins. 

Wheels  are  26  x  4  in.,  shod  with  Goodrich  Cord  Tires. 
Re-enforced  stub  axles  of  nickel  steel  operate  in  metal 


SI.\(;LK  .MOTOKKD  AKKOIM.  \\  i  - 


guide,  with  floating  type  shock-nbsorlH-rs  assembled   onto 

Illl-t.-ll     spools. 

Axlrs.  spreader  tubes  and  sliock-ahsorhi  r  group  well 
streamlined  with  stamped  metal  housings. 

"  V   "     members     of     rll.-l-.--i-,     are     nf     si  leeti  d      brut      ash. 

shock  absorbers  of  ( ioodnch  ••„   in.  diameter  clastic  cord, 
cottiin   sheathed.      Wheels    fitted    with    detachable   st  • 
line   fnlirir  on  ITS  .-mil   special   oiling  device. 

••y   IIII-III|MT   in   tin-   complete   chassis   unit   is   pin  con- 

.    with  adequate  s.-it.t\  lurks,  givinu  -f  at  demount 

ability,   desired    llcxihility   ;ind  case   of   production, 

Met  il  parts  finished  in  lilur  enamel,  baked  on,  while 
wood  memhiTs  .-in  jjheii  thn.  oi.-its  nt  water-proof  var- 
nish. 

Tail-Skid 

I       itiiii:  type  skid,  semi  inmersal  and  si-lf-nlipiin^  in 
actic  n.       Is    fitted    with    riil>ln-r    cord    sliork-alisorlier.s    and 
ilile     mi  tal     shoe.      Assemlily     ^rt-at-ablc     through 
doors  in  ,idi    of  fnsclngf.      All  |iarts  (|uick-detaehnble. 

Radiator 

Sp.  .i,l  hoiie\  eomli  t\pe.  located  iii  nose  of  fuselage, 
hoiisrd  ill  polished  aluminum  shell.  Is  eipiipped  with 
dash  hoard  controlled  slnitti  r  s\stem  to  reflate  ciM>ling. 
Total  water  capacity  in  circulating  system  is  ;pl  ,  gallons, 
distance  water  thermometer  installed. 

Oil  radiator  protruding  Ix-low  the  under  cowl  is  pro- 
vided  in  the  oiling  system.  Including  the  capacity  of  the 
oil  tank,  the  circulating  s\  stem  hold.s  a  total  of  five  gal- 
lons of  Inliricating  oil.  sufficient  for  over  four  hours  wide 

i  n  tl\  ing. 

Fuel  Tanks 

Two   in   numlier,   main   under   rear  seat,  other  in  cowl 
M    i  n^iiie    and    dash-hoard,    front    cock-pit.     Total 
fuel  capacity  is  ;i I  gallons,  sufficient  for  over  2*4  hours  at 
wide  open  throttle  around  sea-level. 

Carburetor  supplied  liy  mechanical  pump  incorporated 
in  motor.  Hand  air  pump  on  dash  for  starting. 

Fin  1  shut  otl'  cocks  in  both  cock-pits. 


Mufflen 

sheet   steel  tubular  exhaust   pipes  extending   along 
.sides  of   fusel  ii;,    back    to   rear  cock  pit.  one   on  ,  a,  b   >,d. 
1'ipis  supported  by   forced  S«IM-|  brackets. 

Control* 

Dual  stick  control  of  new  d.  SIUMI.  comliined  with  stand- 
ard type  adjustable  fi>ot  rudder  bars.  Control  syst. 
semblcd  as  unit  ami  installed  with  k  bolts  only.  Knginr 
throttle  lever  and  altitude  adjustment  control  pn.\  id.  d  in 
both  cockpits.  Starting  magneto  crank  in  rt-ar  cock -pit 
only.  All  controls  have  thumb-screw  tension  locking  de- 
rfaM.  I. \.rs  and  parts  nickel  plated,  polisl  ,  ,| 

Starting 

Self-starting  of  engine  obtaimd  by  special  hand  oper- 
ated .starter  magneto.      Rear  dash  cijuippcd  with  I.unken 
In  iinir   hand    primer   to   motor   to   facilitate   cold   weather 
starting. 

Safety  ignition  switch  visible  to  mechanic  cranking  also 
provided. 

Instruments  and  Equipment 

Altimeter,  air  sp<  . -d  indicator,  \\althim  clock,  tacho- 
meter, gasoline  and  oil  pressure  gauges,  primer.  Boyce 
I..  1).  thermometer,  fuel  controls  and  Dixie  switch,  all 
arranged  on  unit  dash-board. 

Equipment  includes  fire  extinguishers,  safety  belts,  small 
tools  roll  and  miscellaneous  small  parts  replacement  kit. 

Engine 

Hispano-Suiza,  8  cyl.,  130  h.p.,  water-cooled  type, 
Model  A. 

Propeller 

Liberty  2-bladcd,  walnut,  8  ft.  4  in.  diam.  x  5  f t  5' - 
in.  pitch. 

Factor  of  Safety 

A  uniform  factor  of  safety  of  U  plus  has  been  proved 
for  the  design  by  the  latest  French  methods  of  sand  load- 
ing. 


» 


e  Three-Motored  White 
Monoplane 


Tin      dimensions     of     the     White 
lonoplnnes  are: 

spread.     82     f  eet ;     length 
vcrall.    39    tot;    height    to    top    of 
weight  empty.  .S.7HO 
omul-.      Total       Inirscpowi  r.      660. 
d     by     three     Hispano-Sui/.a 
lues.     Two  I  so  H.  P.  engines  are 
itnl  .me  on  each  wing  on  each  side 
-•dy.      The  third  engine.  .SOU 
1     I'  .  ;s  installed  in  the  nose  of  the 
^•B  as   in   single-motored   aero- 
Tin-    winas    have    a    sweep- 
u-il  tips  and  an  angle  of  in 
of  four  degrees. 


120 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  "  Standard  "  Type  E-4  Mail  Plane,  which  has  a  capacity  for  carrying  180  pounds  of  mail. 

engine  the  machine  makes  a  speed  of  100  m.p.h. 


With  an  Hispano-Suiza  150  h.p, 


The  Standard  Model  E-4  Mail  Aeroplane 


Mail  is  now  carried  between  New  York  and  Washington 
in  the  specially  built  "  E-4  "  mail  machine  brought  out 
by  the  Standard  Aero  Corporation. 

General  Dimensions 

Span,  upper  plane    31  ft.  4%  in. 

(Span,  upper  plane  with  overhang)    39  ft.  8%  in. 

Span,   lower   plane    31  ft.  4%  in. 

Chord,  both   planes   6  ft.  0  in. 

Gap  between  planes   5  ft.  6  in. 

Stagger      5y4  in. 

Length    overall    26  ft.  1  in. 

Height   overall    10  ft.  lOy^  in. 

For  winter  flying,  overhang  extensions  are  attached  to 
the  ends  of  upper  wings,  increasing  the  span  from  31  ft. 
4%  in.  to  39  ft.  8%  in. 

Areas 

Square 
Feet 

Upper   plane    1T4.9 

( Upper  plane  with  overhang)    230.3 

Ailerons  (2  upper  and  2  lower)    48. 

Ailerons   (with  overhang)    56. 

Lower    plane    162.1 

(Total  wing  area,  with  overhang)   382.4 

Stabilizer      23.7 

Elevator     22.0 

Fin     4.6 

Rudder     10.1 

Weights,  General 

Pounds 

Machine   empty    1,566 

(Machine  empty,  with  overhang)    1,616 

Fuel  and  oil   .". 390 

Useful  load    444 

Total  weight,  loaded    2,400 

(Total  weight,  loaded,  with  overhang)    2,450 

Weight  per  h.p 14.1 

Weieht  per  sq.  ft 7.12 

(With  overhang;  weight  per  h.p.)   14.4 

(With  overhang;  weight  per  sq.  ft.)    6.4 


Summation  of  Weights 

Weight 
(Ihs.) 

Power    Plant     778.5 

Fuel  and  Oil   390. 

Pilot  and  miscellaneous  equipment  ....     364.3 

Mail    180.0 

Body   Structure    288.1 

Tail  surfaces  with  bracing  75.5 

Wing   structure    324.0 

Chassis     100.0 


Percentage  of 

Gross  Weight 

32.4 

16.2 

11.0 

7.5 
12.0 

3.2 
13.5 

4.2 


Total    2,400.0 


100.0% 


WEIGHT  SCHEDULE 
Power  Plant 

Pounds 

Engine  complete  with  carburetor  and  ignition  system 455 

Radiator 74.5 

Water      75 

Fuel  and  Oil  Tanks  empty    50 

Propeller  and  Hubs   27.5 

Cowling    61.5 

Pipes,  etc 35 

Total      778.5 

Fuel  and  Oil 

Fuel    (60  gallons)     360 

Oil   (4  gallons)    30 


Total     390 

Pilot  and  Equipment 

Pilot  and  clothing    170 

Dashboard    Instrument ;    32.25 

Miscellaneous      62 


Total      264.3 


Mail 


Mail 


180 


Total      180 


SIXCJLK   MOTOKK1)   A  KKO1M.AN  KS 


Uody    frame 


Body  When    overhang   section    is    used,   top   of    inclined    struts 

irt    i  i  uteri  d    I    ft.    s'_.    in.    from   outer   struts,   leaving  an 

o\erhang  of  -.'•.''  -.  in. 
vats    ami    Moor II. .1 

Kront  ami  rear  control   .':'.7:,  I''"'  "  Spad  "  truss  is  used  between  the  planes,  having  a 

—      steel    tul>e   coinpression    member    l«-t«.  en    front    and    rear 
Total      -'--.!         middle  struts.  » here  Hying  and  landing  cables  cross. 

Tail  Surfaces  with  Bracing 

Fuselage 

ili/.rr     .4.0 

•'.lectors      I  •••'•  The  engine  is  carried  on  a  pyramid  type  support. 

Mail   is  carried   in  a  compartment   situated  at   the  center 

{udder      9.5          ,  .          ,  . 

....  .?,  «      of  gravitv.  |iist  forward  of  the  pilot  s  cockpit. 

I.I',,    I  it  I II  iu  ^t    w  I  ri  •»,    (it vi.tj 

\\hen  the  uiaeliine   is  at   rest,  the   propeller  axis  is  (5  ft. 

Total      T.i.j      0  in.  above  ground;  in  Hying  position  it  is  .">  ft.  (I  in.  above 

Wine  Structure  ground.      In    Hying   position,    a    line    from    wheel    base    to 

.„  .       center  of  gravitv  makes  a   11"   angle  with  a  vertical  line. 
I  pper   wmjr  with   lilting   and   ailerons    143.4 

Lower  wimr«itli  lilting  ami  ailerons  129.4  A"-r1'    between   lin.    joining  wheel   base  and   skid  to  a 

Interplane   Struts   and   cables    .1.  liori/ontal    line.    II    d<  -•  minutes. 

Tlie  stabilizer  is  fixed  at  a  neutral  angle. 

Total  3-M.il 

Chassi8  Landing  Gear 

Wheels  eo-nplete;   Axle;  Shock   Alisorber,  and  I'nrts •'•> 

{  Wli.-el  Type  l.andinir  (Scar   93          The  usual  two-wheel  landing  gear  is  used,  hut  provision 

is  made  for  the  attachment  of  a  third  wheel,  ax  shown  in 
the  drawing,  which  adds  25  Ibs.  to  the  weight. 

Performances  Steel    tube   is    used    for   chassis    members,    faired    with 

Height  Speed          Timeof  Climli      Rate  of  Climb         spruce  streamline  stiffening  pieces. 

(ft.)  (m.p.h.)  (min.)  (ft.  per  min.) 

0  100  0  700 

.WM)  10  Engine  Group 

10.000  ...  24 

S, „.,.<!    40  m.p.h.          The    engine    is    a    Wright-Martin    Model    I    Hispano- 

Vi'i-'l'-    1  to  8      Suiza,   giving   150   h.p.   at    1500   r.p.m.   and    170   h.p.   at 

Maximum    Range    280  miles       l7()OrDm 

Hours  ruL'lit.  full  speed  at  4,000  feet   3  hours  ,        ,  . 

The  model  I  is  an  8  cylinder  V  type  with  a  bore  of  120 

Main  Planes  mm.    (t.724   in.)    and   a   stroke  of    ISO  mm.    (5.118   in.). 

Both  planes  are  swept  back  at  a  5°  angle,  and  both  have  Zenith  Carburetor  and  magneto  ignition  are  used. 
a  r;    or  1%°  dihedral.     There  is  no  dccalage;  the  inci-  F.ngine    weight,    with    propeller.     155    Ibs.     Propeller, 

or  angle  of  the  wing  chord  to  the  propeller  axis  is  9  ft.  0  in.  in  diameter. 

oi..  Fuel  consumption,  0.51  Ibs.  per  h.p.  per  hour;  oil  con- 
Wing  section.  R.A.F.  15.  Aspect  ratio  of  both  wings,  sumption,  0.03  Ibs.  per  h.p.  per  hour.  Fuel  tanks  are  lo- 
«-hen  overhang  section  is  not  used.  cated  at  the  center  of  gravity;  their  capacity  is  60  gallons. 
I'ops  of  center  section  struts  are  spaced  32%  in.  from  Oil  tanks  located  underneath  the  engine;  capacity,  4  gal- 
cent,  r  to  center.  Middle  struts  5  ft.  8  in.  from  center  Ions, 
•ection  struts;  outer  struts  6  ft.  3  in.  from  middle  struts.  The  nose  radiator  is  of  the  Livingston  type.  Water 
This  leaves  an  overhang  of  331/;:  in.  capacity,  9  gallons. 


Three-quarter  rear  view  of  the  Standard   Model  E-4  Mail   Aeroplane 


Compartment    for  carrying  mail   on 
Hi,      "  Standard "     Mall     Aeroplane 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Thomas-Morse  S-4C  single  sealer  advanced  training  scout  with  an  80  h.p.  Le   Rhone  engine 


Typt 


Thomas-Morse 
-S-4C  Single-seater  Scout 


General  Dimensions 

Length    19  ft.  10  in. 

Spread 26  ft.  6  in. 

Height    8  ft.  1  in. 

Weight  and  Lift  Data 

Total  weight  loaded '. 1330  His. 

Area  lifting  surface  (including  ailerons)   234  sq.  ft. 

Loading  per  sq.  ft.  of  lifting  surface  5.7  Ibs. 

Required  horse  power 90 

Weight  of  machine  loaded  per  h.p 14.8 

Power  Plant 

Type  of  engine 80-h.p.  Le  Rhone  (air  cooled  rotary) 

Engine  revolutions  per  minute  1250 

Fuel  capacity,  30  gallons,  sufficient  for  3%hours'  flight  at  full 

power 
Oil  capacity,  6   gallons,  sufficient  for  4</2   hours'   flight  at  full 

power 

Propeller  type  2  blade 

Propeller  diameter  8  ft. 

Propeller  revolutions  per  minute    1250 

Chassis 

Type  "  Vee  " 

Wheels 2  (tread  5  ft.) 

Tires  26  in.  x  3  in. 

Area  Control  Surfaces 

Ailerons 25      sq.  ft. 

Elevators 16.8  sq.  ft. 

Rudder    8.5  sq.  ft. 

Horizontal  stabilizer   16.8  sq.  ft. 

Vertical   stabilizer    3.5  sq.  ft. 

Stick  type  control  used. 

Performance 

High  speed    9T  miles  per  hour 

Low  speed    45  miles  per  hour 

Climb  in  first  ten  minutes   7500  ft. 

Thomas-Morse 
Type — S-4E  Single-seater  Scout 

General  Dimensions 

Length    19  ft.  4  in. 

Spread   22  ft.  6  in. 

Height   7  ft. 


Weight  and  Lift  Data 

Total  weight  loaded   1 150  Ibs 

Area  lifting  surface   (including  ailerons)    145  sq.  ft 

Loading  per  sq.  ft.  of  lifting  surface  S  Ibs 

Required  horse  power    '. 9( 

Weight  of  machine  loaded  per  h.p 12.S 

Power  Plant 

Type  of  engine 80-h.p.  Le  Rhone  (air  cooled  rotary j 

Engine  revolutions  per  minute   125( 

Fuel  capacity,  20  gallons,  sufficient  for  Sy2  hours'  flight  at  full 

power 
Oil  capacity,  4  gallons,  sufficient  for  3  hours'  flight  at  full  power 

Propeller  type 2  hlad< 

Propeller  diameter 7  ft.  6  in 

Propeller  revolutions  per  minute  I25( 

Chassis 

Type  "  Vee ' 

Wheels 2  (tread  5  ft.) 

Tires  26  in.  x  3  in 

Area  Control  Surfaces 

Ailerons 16.4  sq.  ft 

Elevators    16.8  sq.  ft 

Rudder    7.3  sq.  ft 

Horizontal  stabilizer   11.2  sq.  ft 

Vertical  stabilizer   3.8  sq.  ft 

Stick  type  control  used. 

Performance 

High  speed    112  miles  per  houl 

Low  speed  55  miles  per  houi 

Climb  in  first  ten  minutes  .  8500  ft. 


Thomas-Morse 
Type — S-6  Tandem  Two-seater 

General  Dimensions 

Length    20  ft.  8  in. 

Spread   29  ft.  0  in. 

Height    8ft.  10  in, 

Weight  and  Lift  Data 

Total  weight  (loaded)    13S.1  Ibs. 

Area  lifting  surface  (including  ailerons)    296  sq.  ft. 

Loading  per  square  foot  of  lifting  surface 4.68  Ibs. 

Required  horse  power 

Weight  of  machine  (loaded)  per  h.p 15.4  Ibs. 


SINCil.K   MOTOKK1)   .\KHO1M..\.\KS 


128 


Tile    Thomas-Morse    Type    S     I       I      Ills    ;i    uilll.'    spi-enl    ,if     .' .'    fert.        It 

I.e   Khonr.      It    has  a   speed    :  ,,   to    ||.'  m 

Power  Plant 

»f  ciiirine so-h.p.  I..-  Khonc  (air  coolrtl  rotary) 

Kiigine  rcMilutinns  per  miniiti-   

I  M.  I  raparit}.   Jn  gallon-.,   snffirient    for  ly,  hours'  flight  at   full 

power 
Oil  raparity.   t  gallons,  sufficient  for  :t  hours'  flight  at  full  |x>wer 

Propeller    t}  |H-    _>    |,lnde 

Pni|»'llrr  diameter    7   fj     ]<>   jn 

I'roprllrr    reinliitions   |x-r   ininutr    I 

Chassis 

-  Vee  " 

-1  (tread  5  ft.) 

T'ri"   M  in.x3  in. 

Area  Control  Surfaces 
Ail,  n.ns:    (four)     31.5  gq.  ft. 

••'•''•>  ••''•"•-     16*  sq.  ft. 

Kuddrr     8.5  sq.  ft. 

I  lori/nntal   stabilizer    14.5  M|.  ft. 

Vertical    stabili/.rr    3.5  sq.  ft. 

Stick  tvpr  control  used. 

Performance 

High   speed    105  miles  per  hour 

I  .,m   s|ieed   40  miles  per  hour 

Climb  in  first  ten  minutes 8000  ft.        T}  |n- 


I.I.VI    pounds    and    is    powered    with    an    H<|    horsr-pourr 
iles  per  hour  and  1 1  feet    in    ID  minutes. 

Thomas-Morse 
Type — S-7  Side-by-Side  Two-seater 

General  Dimensions 

">    .'I  ft.  i,  in. 

Spread     't '  ft 

Height 9  ft 

Weight  and  Lift  Data 

Total    weight    loaded    1480  Mis. 

Area  lifting  surface  (Including  ailerons)    3ti  M\.  ft. 

Loading  per  square   foot  of  lifting  surface    4.«  Ibs. 

Kequiml    horse    power     ..90 

Wright   of   machine    loaded   |>er   h.p 16J  Ibs. 

Power  Plant 

Ty|«-  of  engine 80-h.p.  I.e  KhSne  (air  cooled  rotary) 

Kngine  revolutions  |>er  minute  i  .'.JD 

Fuel  capacity,  X)  gallons,  sufficient   for  1' ..  hours'  flight  at   full 

power. 
Oil  rapacity,  •  gallons,  sufficient  for  3  hours'  flight  at  full  power. 

Propeller  ty|>e  .'-blade 

Proprllrr  diameter 8  ft 

Pro|)eller   revolutions   p<-r   minute    

Chassis 


Vee' 


view  of  the  Thoma>-Mors< 


wing  fitting  at  the  left  outer  strut, 
Thomas-Morse  Siile-liy-Side  Tractor; 
an  eye-bolt  running  through  the  turn- 
buckle  plate  attaches  the  strut  fitting 
to  the  wing  beam 


124 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Thomas-Morse  S-7  80  h.p.   Le   Rhone  engine,  side-by-side  two-seater,  designed  particularly   for  pleasure  flying. 

Wheels 2  (tread  5  ft.)        Vertical   stabilizer    li.G  sq.  f.t 

Tires 26  in.  x  3  in.  Stick  type  control  used. 

Area  Control  Surfaces  Performance 

Ailerons:  (four)   40      sq.  ft.       High  speed    90  miles  per  hour 

Elevators     16.8  sq.  ft.       Low  speed    40  miles  per  hour 

Rudder    8.5  sq.  ft.       Climb  in  first  ten  minutes  6TOO  ft. 

Horizontal  stabilizer   14.5  sq.  ft. 

The  Thomas-Morse  Type  M-B-3,  300  H.P.  Hispano  Engine  Fighter 


-Streamline  cap  at  wire  crossing,  middle  interplane  strut.  2 — T.eft  lower  front  strut  socket.  3  —  Empennage,  showing  the  un- 
usual arrangement  of  the  elevator  lever  which  is  run  on  the  inside  of  the  vertical  fin.  4 —  Operating  arm  on  top  of  upper 
aileron.  At  the  right  is  shown  a  sketch  of  the  unique  junction  for  attaching  streamline  wires  to  flexible  aileron  control  cable. 


Thomas-Morse  type  MB-U  single-seater  fighter,  equipped  with  300  h.p.  Hispano- 
Suiza  engine.  Span,  26  ft.;  length  over- all,  20  ft.;  height,  9  ft.  1  in.  Total 
weight  loaded,  2050  pounds.  Fuel  and  oil  capacity  for  three  hours'  flight  at  full 
power.  High  speed  —  163  2/3  m.p.h.,  climb  to  10,000  feet  in  4  minutes  52 
seconds. 


SIMil.K  MOTOKKI)  AEROPLAN]  - 


<       _  .  .».  *.v  ~  "  .A  •*•  "I- rv  •— .  Z..7T  —   —  —  ^ 


^iwl,!,!,.!,!^  ,li 


(irm-ral  urrHiigi-iin-iit,  and  MMIW  dt  tails,  of  the  Frrnrh  A.H.  biplane 


h 


/-„/»<«   C/./f  . 


T^.. ,       *~+-*~t, 

-C-^J /      O^mnjjor  C»-» 

Ji^VWJ- 


FRENCH  A  .R.  TyP«  /. 


Plan   and  elevation  of  the  fuselage  of  the   French   A.  R.  biplane 


126 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Four  views  of  the  French  A.R.  biplane 

The  French  A.   R.   Biplane 


This  machine,  designed  by  Commander  Dorand,  of  the 
French  Army,  is  designated  as  A.  R.  or  A.  L.  D.,  according 
to  whether  it  is  fitted  with  a  Renault  or  with  a  Lorraine- 
Dietrich  engine.  The  machine  is  a  two-strutter  biplane 
of  13.30  m.  span,  and  has  its  fuselage  supported  between 
the  planes  on  ash  struts.  Sweep-back  and  dihedral  angle 
are  only  present  in  the  lower  plane.  The  former  amounts 
to  1  deg.,  while  the  dihedral  angle  is  2  deg.  The  top 
plane  is  staggered  backwards  0.5  m.  The  gap  is  1.825 
and  2  m.,  respectively;  that  is  to  say,  in  the  centre  it  is 
0.945  of  the  chord.  The  angle  of  incidence  of  the  upper 
plane  is  2.5  deg.,  that  of  the  lower  plane  3  deg. 

The  halves  of  the  wings  are  screwed  together  in  the 
centre  of  the  machine.  The  wing  spars  appear  to  be  of 
one  section,  covered  on  both  sides  with  three-ply.  Be- 
tween every  two  ribs,  whose  spacing  is  300  to  340  mm.,  is 
a  short  false  rib  on  the  top  surface  only,  running  from 
the  leading  edge  to  the  front  spar.  The  wing  fabric, 


which  is  of  a  cream  color,  is  sewn  to  the  ribs.  In  front 
of  the  trailing  edge,  which  is  formed  by  a  wire,  as  in  all 
French  machines,  eyelets  are  incorporated. 

The  plane  struts,  which,  with  the  exception  of  those 
secured  to  the  body,  are  of  hollow  section,  are  of  stream- 
line form.  In  order  to  prevent  lateral  bending  the  outer 
plane-struts  are  provided  with  a  peculiar  bracing.  In 
addition  the  middle  of  the  struts  are  braced  to  one  another 
and  to  the  bottom  of  the  body  struts.  The  strut  fittings 
are  of  a  very  simple  type,  as  shown  in  one  of  the  illustra- 
tions. Strut  sockets  of  sheet  steel  are  secured  to  the 
spars  bv  U  bolts,  the  two  shanks  of  which  pass  through 
the  spar  and  are  secured  by  nuts  on  the  other  side.  The 
flying  wires  and  landing  wires  are  anchored  to  the  corners 
of  these  U  bolts,  while  the  incidence  wires  are  secured  to! 
lugs  projecting  from  and  forming  part  of  the  steel  plate 
bottom  of  the  strut  sockets.  This  bottom  is  simply  resting 
inside  the  socket  and  is  not  secured  in  any  other  way. 


SINCil.K   MOTOKKI)  A  KHOl'LA.N  KS 


r-'T 


The  wing  bracing  consists  of  solid  wires  throughout, 
whifh  arc  corniced  d  to  tin1  fittings  :iiul  turnlmrklrs  in  the 
usual  way  by  bending  them  OMT  and  sliding  a  ferrule  of 
spiral  wire  OMT  the  free  end.  The  Hying  wires  are  in 
dii|ilie:ite  and  lie  line  In  hind  the  other.  The  space  be- 
tween them  is  tilled  with  a  strip  of  wood.  The  external 
drift  wire  running  to  the  nose  of  the  Imdy  is  wrapped  with 
thin  cord  to  prevent  it  becoming  entangled  in  the  propeller 
in  ease  of  breakage.  Hctuccn  the  fuselage  and  the  lower 
plane  there  is  diagonal  bracing  in  the  plane  of  eaeh  spar. 
As.  howe\er.  there  is  no  corresponding  bracing  aho\e  the 
fuselage,  the  upper  ends  of  the  top  plane  body  struts  are 
allow  eil  a  eoiisideralile  amount  of  play. 

\on  hal meed  ailerons.  positively  operated,  are  hinged 
direet  to  the  rear  spar  of  the  top  plane  only.  The  aileron 
eontrol  cables  are  in  the  form  of  simple  cables  running 
from  the  sprocket  wheel  on  the  control  column,  around 
pulleys  in  the  lower  plain-,  along  the  lower  side  of  the 
lower  plane  and  under  another  pair  of  pulli  \  s.  From  this 
point  on  tin  \  are  in  the  form  of  solid  wires  of  2  mm. 
diameter  riinnini;  to  the  aileron  crank  lexers,  which  are  in 
the  form  of  quadrants.  The  upper  cranks  of  the  ailerons 
are  connected  by  cables  and  wires  running  across  from 
side  to  side,  along  the  upper  surface  of  the  top  plane. 

At  tin-  stern  of  the  fuselage  is  fixed  a  small  tail  plane  to 
which  is  pivoted  the  balanced  trapezoidal  elevator.  The 
rudder  is  also  balanced.  The  rudder  post  is  braced  to  the 
cletator.  and  this  in  turn  to  the  body,  by  stream-line  steel 
tube  struts.  The  ends  of  these  struts  are  flattened  out 
and  bolted  to  the  various  fittings.  There  is  no  vertical  fin. 
The  rudder  is  controlled  by  plain  wires  of  2.5  mm.  diam- 
eter. Only  where  they  pass  over  pulleys  have  cables  been 
substituted  for  the  wires. 

The  undercarriage  struts  are  secured  to  the  spars  of  the 
lower  plane  at  the  points  where  occur  the  attachments  for 
the  struts  running  to  the  body.  The  short  body  struts  are 
braced  by  stream-line  tubes  fore  and  aft  to  the  body.  The 
one-piece  axle  rests  between  two  cross  struts  of  steel  tube. 
The  travel  of  the  axle  is  not  restricted.  The  undercar- 
riage is  braced  diagonally  in  the  plane  of  both  pairs  of 
struts. 

Tin-  longerons  and  struts  of  the  fuselage,  which  is  fabric 
covered,  are  made  of  ash  up  to  the  observer's  seat.  From 
there  they  are  made  of  spruce.  The  struts  of  the  rear 
portion  of  the  fuselage  rest  on  the  longerons  without  any 
attachment,  and  are  held  in  place  by  the  bracing  only. 
To  prevent  them  from  sliding  along  the  longerons  the 
ends  of  the  struts  are  notched  to  correspond  with  the  shape 
of  the  wiring  lugs,  which  surround  the  longerons. 

The  8-cylinder,  Vee  type  Renault  motor  develops,  ac- 
cording to  a  plate  in  the  pilot's  cockpit,  190  h.p.  at  1550 


to  1  tii MI  r.p.m.  The  radiator  is  placed  between  the  body 
and  the  lower  plane.  Then  is  a  shutter  arrangement  for 
varying  the  cooling.  A  water  collector  or  (.ink  is  placed 
above. the  port  row  of  cylinders.  The  exhaust  gases  are 
carried  outwards  to  cadi  side  through  short  collectors. 
\\'ith  the  older  motors  the  exhaust  from  both  row»  of 
cylinders  was  carried  inwards  to  a  common  collector  car- 
rying it  up  above  the  top  plane,  an  arrangement  which 
greatly  hampered  the  \  n  w  of  the  pilot.  In  these  machines 
the  radiator  was  in  the  nose  of  the  body.  An  auxiliary 
radiator  was  placed  In-low  the  fuselage. 

The  motor  is  bolted  to  two  channel  section  steel  bearers, 
which  rest  on  strong  sheet  st,  ,  I  cr  idles.  Imm.diit.  Iv  be- 
hind the  engine  is  placed  transversely  the  oil  tank,  which 
has  a  capacity  of  7  litres.  Tin-  main  petrol  tank,  which 
has  a  capacity  of  I7<»  litres,  is  divided  into  three  com- 
partments, and  :•>  placed  behind  the  pilot's  seat.  From 
here  the  petrol  is  pumped  into  a  small  gravity  tank  holding 
1-'  litres  and  placed  behind  the  engine.  For  this  is  em- 
ployed either  a  pump  driven  by  the  engine  or  a  hand  pump 
to  tlw  right  of  the  pilot.  If  too  much  petrol  is  pumped 
through  it  is  returned  to  the  main  tank  via  an  overflow. 

The  pilot  sits  in  a  line  with  the  leading  edge  of  the  top 
plane.  Here  he  has  a  very  good  view  forward,  but  the 
view  in  a  rearward  and  upward  direction  is  very  restricted. 

On  the  instrument  board  in  front  of  the  pilot  are  the 
following  instruments:  A  cooling  water  thermometer, 
ignition  control,  compass,  petrol  cock  and  revolutions  in- 
dicator. To  the  right,  at  the  side  of  the  scat,  is  the  petrol 
hand  pump  elevator.  On  the  left  are  the  levers  for 
advancing  or  retarding  the  ignition,  the  petrol  and  air 
levers,  the  radiator  shutter  control,  and  the  oil  cock.  In 
the  floor  of  the  fuselage,  in  front  of  the  rudder  bar,  there 
are  small  windows. 

In  the  observer's  cockpit  there  are  two  folding  seats, 
one  in  front  and  one  at  the  rear.  In  front,  behind  the 
petrol  tank,  there  are  on  each  side  racks  for  four  bombs. 
Between  these  racks,  through  an  opening  in  the  floor,  the 
photographic  camera  can  be  inserted.  A  shelf  for  plate 
holders  is  placed  behind  the  port  bomb  racks.  On  the 
starboard  inner  wall  of  the  observer's  scat  are  aluminum 
plates  for  the  switches  and  keys  of  the  wireless.  The 
other  instruments  of  the  wireless  are  placed  aft  of  the 
seat. 

The  pilot  is  armed  with  a  fixed  machine  gun  placed  on 
the  right-hand  side  above  the  body,  and  is  operated  from 
the  left  cam  shaft.  Firing  is  accomplished  by  Bowden 
control  from  the  control  wheel.  The  observer  has  two 
movable  machine-guns,  coupled  together  and  mounted  on 
a  gun  ring  with  elevating  arrangements. 


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TEXTBOOK  OF  APPLIED  AKKOXAUTTC  ENGINEERING 


A    French    Breguet   bombing  machine  in   flight.     On   the   rear  can    be  seen  twin  Lewis  guns  mounted  for  use  of  the  aerial  photog- 
rapher or  observer 

The  Breguet  Biplane 


This  biplane,  characterized  by  two  sets  of  struts,  is  pro- 
duced almost  exclusively  of  aluminum,  and  is  intended  for 
bombing  purposes.  The  upper  planes  have  a  backwards 
stagger  of  0.21  m.  and  a  span  of  1-1.4  m.,  and  are  mounted 
on  a  cabane  frame,  while  the  lower  planes  have  a  span  of 
13.77  m. 

Both  upper  and  lower  planes  have  large  cuttings  at  the 
fuselage  and  their  arrow  shape  amounts  to  175  deg.  The 
angle  of  incidence  of  the  upper  planes  is  4.5  deg.  in  the 
middle  and  2.5  deg.  at  the  ends,  that  of  the  lower  ones 
decreasing  from  3  deg.  to  2  deg. 

The  spars  of  both  planes  are  drawn  aluminum  tubes 
of  rectangular  section  65.6  x  31.6  mm.  The  thickness  of 
the  walls  of  these  tubes  amounts  in  the  inner  section  of 
the  upper  plane  to  2.6  mm.,  elsewhere  to  1.6  mm.  The 
rear  spar  grows  thinner  towards  the  wing  tips  till  the 
thickness  of  the  edge,  where  auxiliary  spars  with  ash  bands 
of  6  mm.  thickness  and  3  mm.  three  plywood  glued  to  both 
sides  are  provided.  At  the  points  of  juncture  and  at  the 
ends  of  the  stampings  the  spars  are  strengthened  by  ash 
pieces,  in  some  instances  of  I  shape.  A  socket  of  20  cm. 
length,  made  of  welded  sheet  steel  of  a  thickness  of  1.5 
mm.,  is  provided  at  the  strut  ends  of  the  upper  planes  and 
at  the  strut  bases.  These  sockets  and  the  wooden  linings 
are  held  in  position  by  iron  tube-rivets. 

The  main  spar  of  the  upper  plane  is  strengthened  in  the 
interior  section  of  a  pine  support  of  a  thickness  of  10  mm. 
being  fixed  to  one  side  of  the  spar  by  means  of  small 
brass  screws.  The  spars  of  the  upper  planes  are  equipped 
with  compression  supports  at  the  joints  of  the  two  sets  of 
struts  and  the  lower  planes  for  the  outer  strut  set,  the 
support  being  an  aluminum  tube  of  the  diameters  30  and 


27  mm.  exterior  and  interior.  Further  there  are  two 
aluminum  ribs  of  a  width  of  40  mm.,  one  at  the  beginning 
of  the  ailerons  and  one  by  the  bomb  store  in  the  lower 
plane.  The  interior  wiring  consists  of  single  wire. 

The  ribs  are  very  strong.  They  have  a  depth  of  2  mm. 
above,  of  1.9  below.  A  web  provided  with  weight  dimin- 
ishing holes  is  glued  between  the  longitudinals  of  three- 
ply  wood,  3  mm.  thick.  On  both  sides  of  the  spars  as  well 
as  at  five  points  between  them  the  flange  is  strengthened 
by  glued  and  nailed  birch  laths  and  wrapped  bands.  The 
ribs  are  arranged  loosely  on  the  spars.  The  ribs  lie  par- 
allel to  the  axis  of  longitude,  forming  in  relation  to  the 
spars  an  angle  corresponding  with  the  arrow  shape.  They 
are  connected  with  each  other  by  means  of  the  veneer 
planking,  reaching  on  the  upper  side  from  the  leading 
edge  to  the  main  spar,  as  well  as  by  the  leading  and  trail- 
ing edges.  Further  they  are  connected  by  two  bands, 
lying  behind  each  other  and  alternately  wound  from  above 
and  below  the  ribs.  The  distance  between  them  amounts 
to  40  mm.  Forward  and  in  front  of  the  rear  spar  more 
1  mm.  thick  auxiliary  ribs  of  plywood  are  arranged.  To 
reinforce  the  aerofoil,  thin  birch  ribs  reaching  to  the  trail- 
ing edge  are  screwed  to  the  rear  of  the  ribs  on  the  under- 
side. 

The  yellow-white  colored  fabric  is  sewed  to  the  ribs 
and  secured  with  thin  nailed  strips  where  exposed  to  the 
air-screw  draught.  The  provisions  of  hooks  and  eyes  on 
the  under  side  of  the  planes  behind  the  leading  edge  and 
in  front  of  the  trailing  edge  is  to  permit  the  draining  off 
of  moisture. 

The  part  of  the  lower  plane  lying  behind  the  rear  spar 
is  hinged  along  its  total  length  and  is  pulled  downwards  by 


SIMil.K   MOTOKK1)   AKKOl'l.AM.s 


in'  in-,  of  I -J  nil. In  r  cords  fi\.d  on  tin-  under  s.de  ..I  the 
ribs,  tlu-  tension  of  these  r.-m  IM  adjusted  In  means  •  >< 
scr.ws.  .in  :iiitoin;itic  cli.in^i  ot  tin-  :iiTiif<ii|  corrcspondin:; 
with  tin-  load  and  speed  thus  results  with  ;in  easier  rontrol 
of  tin  aeroplane  with  .-mil  without  .1  lo  ul  nt  bombs.  The 
-'  [lupines  lur  tin-  dinars  of  tin-  ailerons  ;tnil  tin  flexible 
lower  plane  pieces  cmliracc  the  spars  anil  in  connected 
with  them  I >y  means  of  liolts  passim;  riijlit  through.  Tin 
spars  hail-  no  linings  at  thesr  po.nls. 

The  coiistrm  (ion  of  tin  stampings  nf  the  spars  is  \<r\ 
simple.  Several  sheet  steel  pieces  with  corresponding 

in    fixed   to   tin    spars   with   two  screws   p 
tratiiij;  them. 

The  interplaiie  struts  are  made  of  streamlined  aluminum 
tiilies  with  aluminum  sockets  in  lioth  ends.  The  inner 
struts  are  further  str<  -ngtln  neil  liy  tin-  insertion  of  rivcteil 
(  irons.  The  aluminum  employed  his  a  stn  iii;th  of  H> 
kg.  |>er  s(|.  Him.  with  a  stretching  of  18  per  rent.  The 
l»  ndinj:  figure  is  I  —  2. 

The  I-..!  nun.  thick  load-carrying  cables  are  double,  the 
spaee  lietwicn  tin  in  being  tille<l  by  a  wooden  lath.  In  the 
same  manner  the  landing  wires  as  well  as  those  crossing 
from  the  up|M-r  planes  forward  and  backwards  of  the 
fust-lap-  are  arranuid.  In  inj;  wires  of  a  thickness  of  •.''- 
mm.  that  are  connected  with  the  .stampings  and  the  turn- 
buckles  in  a  primiti\e  way  |i\  means  ot  CMS  and  spiral 
wire  pushed  over.  To  give  a  l>t-ttcr  support  to  the  lower 
planes,  beinir  much  stressed  by  the  |MIIII|I  .store,  the  load- 
carrying  cables  are  in  the  inner  section  led  to  the  stamp- 
ing on  tin  main  ribs  arranged  by  the  ttomb  store,  ami 
them,  downwards  to  the  landing  gear.  The  rear  spar  of 
the  upper  plains  is  also  provided  with  a  cable  to  the 
fuselage  between  the  c.ibane  and  .strut. 

Tin-  stampings  for  the  fixing  of  the  wiring  is  constructed 
\.-ry  simply.  A  bent  sheet  metal  of  L'  form  and  with 
drilled  holes  for  the  bolts  carries  the  nipples  of  the  eye- 
bolts. 

The  Fuselage 

The  canvas-covered  body  consists  almost  exclusively  of 
aluminum  tubes  that  are  riveted  with  welded  steel  tube 


si.  .MX  :i|.l  spanned  with  wire.  Onh  .it  >p.  i-ially  stressed 
points  in  the  front  part  li.-uc  steel  tnU-s  In  i  n  einployi-d. 
Tin  up|K-r  and  lower  sides  of  the  1  i  .  inded 

b\   the  eiii|ilo\ment  of  fairings. 

The  .  iimn.    r.  s|>  on  aliiminiim   I      In  -an  rs   that  art-  sup 
ported   ly    ri\eteil   aluminum   struts.      Two   pairs  of   large 
\iew    trips   an    prox  ided   U-low    the   seats  of   tin-   pilot   and 
olisericr.  and  are  operated   by  cable  by   tin    obs.  rvi  r. 

The  Undercarriage 

The  \cr\  stroiij;  landing  gear  has  three  pairs  of  struts 
of  aluminum  streamline  tubes,  strengthened  \>\  1  irons 
riveted  in.  and  resting  In  low  on  hori/.ontal  steel  tubes. 
Tin-  wheel  shaft  rests  in  an  auxiliary  one  of  steel  sheet 
in  t  shape  welded  on.  The  back  root  points  of  the  strt:ts 
are  connected  by  means  of  a  second  steel  tube  auxiliary 
.shaft,  welded  on,  and  liy  a  tension  hand  lying  behind.  A 
diagonal  wiring  is  further  provided  hori/.ontally  in  tin 
auxiliary  shaft  level.  The  streamlining  of  the  shafts  is 
cut  out  in  the  middle  behind  the  front  auxiliary  shaft  to 
improve  tin  sight  downwards.  There  is  only  a  diagonal 
wiring  to  the  fuselage  in  tin  level  of  the  miilill.  struts. 

The   ash    tail    skid    hangs    in    rubber    springs    from    the 
fuselage   and    is  strengthened   in   the   rear  end   by   a  con-r 
ing  of  a  rectangular  aluminum  tube.      Its  wire  stay  is  sup 
ported  ill  the  rear  stem  by  a  spiral  spring.      Leaf  springs 
are  further  fixed  to  the  end  of  the  skid. 

Tail  plane,  rudder  and  elevator  are  of  welded  thin  steel 
tubes. 

The  aeroplane  is  equipped  with  complete  dual  control. 
The  control  in  the  observer's  cockpit  can  IM-  removed. 

The  ailerons  are  interconnected.  The  twin  control 
<'alil.s  run  behind  the  rear  spar  of  the  lower  planes  to 
two  direction  changing  rollers  resting  on  a  shaft.  Here 
they  part  and  are  led  as  separate  wires  of  thickness  of  2 
mm.  to  the  underside  of  the  aileron.  In  the  upper  plain  s 
the  ailerons  are  connected  by  control  cables,  governing 
two  levers  ill  each  side.  The  ailerons  are  balanced  and 
welded  to  a  common  shaft. 


' 


A  squadron  of  l-'rcndi   Hrejruet  bombing  machines 


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LIFt  BOAT    FORMING  FAIRING 
OF  FUSELACE.  WHICH  CAN      ' 
tO.    INSTANTLY,    RELEASED 
FROM.  -. PILOTS     SEAT 


COCKPIT  FOR  PILOT 

AND  NAVIGATOR 


375  HP  ROLLS  ROYCt 
"EAGLE."  ENGINE 


PETROL  TANK  CAPACITY 
ABOUT  400    GALLONS  FOR 
25    HOURS    FLIGHT 


ENGINE    EXHAUST   PIPE 
TO  ELIMINATE    RISK 
OF    FIRE 


The  Sopwith  biplane,  in  which  Harry  Hawker  attempted  to  fly  across  the  Atlantic 


The  Sopwith  Machine 

The  Rolls-Royce  engined  Sopwith  transport  type  spe- 
cially designed  for  crossing  the  Atlantic,  is  of  the  vertical 


Scale  plans  of  the  Short  and  Sopwith  transatlantic  type  aeroplanes 


liplane  type,  the  wings  having  no  stagger.  Pilot  and 
navigator  are  •  seated  well  aft,  so  as  to  give  a  large  space 
in  the  fuselage  between  them  and  the  engine,  in  which  to 
fit  the  large  petrol  tank  required  for  the  great  amount  of 
fuel  that  has  to  be  carried  for  a 
flight  of  this  duration. 

The  cockpit  of  the  occupants  is  ar- 
ranged in  a  somewhat  unusual  way, 
the  two  seats  being  side  by  side,  but 
somewhat  staggered  in  relation  to  one 
another.  The  object  of  this  seating 
arrangement  is  to  enable  them  to 
communicate  with  one  another  more 
readily  and  to  facilitate  "  changing 
watches  "  during  the  long  journey. 
The  very  deep  turtle  back  of  the  fu- 
selage is  made  in  part  detachable,  the 
portion  which  is  strapped  on  being 
built  so  as  to  form  a  small  lifeboat  in 
case  of  a  forced  descent  at  sea. 

The  Short  Machine 

Fundamentally  the  Short  machine 
entered  for  the  race  does  not  differ 
greatly  from  their  standard  torpedo 
carrier  known  as  the  "  Shirl."  It 
is  a  land  machine  fitted  with  wheels. 
In  the  place  between  the  chassis 
struts  usually  occupied  by  the  tor- 
pedo in  the  standard  "  Shirl  "  is 
slung  a  large  cylindrical  fuel  tank 
which,  should  the  necessity  arise,  can 
be  quickly  emptied  so  as  to  form  a 
float  of  sufficient  buoyancy  to  keep 
the  machine  afloat  for  a  considerable 
period.  In  order  to  be  able  to 
carry  the  extra  weight  of  fuel  neces- 
sary for  the  long  journey  larger 
wings  have  been  fitted,  having  three 
pairs  of  struts  on  each  side  instead 
of  the  two  pairs  fitted  on  the 
standard  machine. 


SIX<;i.K   MOTOKKI)   AKKOIM.ANKS 


131 


The  transatlantic  flight  type  Martlnsyde  hiplane  at  ! 

The  Martinsyde  Type 

Tin-  machine  is  more  or  less  of  standard  Martinsyde 
type,  with  tlir  occupants  placed  very  far  aft  to  allow  of 
mounting  a  large  fuel  tank  in  the  middle  of  the  fuselage, 
in  the  neighborhood  of  the  center  of  gravity  where  the 


decrease  in  fuel  weight  as  the  fuel  is  used  up  will  not 
alter  the  trim  of  the  machine.  In  outward  appearance 
it  does  not  present  any  radical  departure  from  the 
standard.  It  had  the  distinction  of  being  the  lowest 
powered  machine  in  the  race,  the  engine  being  a  Rolls- 
Royce  "  Falcon  "  of  2H/i  h.p. 

The  general  specifications  of  the  Martinsydc  are  as  fol- 
lows : 

Spun.   l«>th   planes    *3  ft.  4  In. 

Chord.   Inith    planes    6  ft.  6  in. 

Gap   lietween   plnnos    5  ft.  6  In. 

Area  of  main  planes  MM)  &q.  ft. 

Overall     length     -'7   ft.  5  in. 

Overall    heiffht     10  ft.   lo  in. 

Fuel    capacity    373  gallons 

Cruisinir   radius    ->.ooo  miles 

Speed     100  to  1«  m.p.h. 

Captain  Frederick  Philips  Raynham,  the  pilot  of  the 
Martinsyde  aeroplane,  went  with  the  Martinsydes  in  early 
development  days  in  l'.K)7  and  was  with  them  when  they 
began  monoplane  production  in  1008.  When  the  war 
began  Martinsydes  turned  to  building  biplanes  and  the 
present  machine  is  but  slightly  modified  from  their  latest 
fighter.  The  machine  for  the  transatlantic  flight  was 
taken  from  stock  and  still  carries  its  original  equipment 
such  as  used  during  the  war. 


The  Martinsyde  "Hayntor' 


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FRONT  ELEVATION. 


SIDE-  ELEVAT.ON. 
Line  drawings  of  the  Grahaine-White  Aero  Limousine  equipped  with   two   210  h.p.    Uolls-Hoyce   motors   and   tractor  propellers. 


Grahame- White   Aero   Limousine 


The  machine  accommodates  four  passengers  and  a  pilot, 
the  latter  in  a  separate  compartment  behind  the  pas- 
sengers, who  have  a  perfectly  clear  view  forward,  down- 
ward and  sideways.  The  limousine  body  is  as  luxuriously 
equipped  as  a  modern  interior-drive  motor-car,  and  is 
equally  commodious.  Unsplinterable  glass  windows,  both 
wind  and  draught  proof,  are  fitted,  and  it  will  no  longer 
be  necessary,  when  using  such  a  machine,  to  clothe  one- 
self specially  for  flying.  The  limousine  has  a  heating  ap- 
paratus, a  ventilating  system,  and  a  speaking  tube  connects 
it  with  the  pilot's  compartment.  A  specially-designed 
system  of  maps,  under  the  control  of  the  pilot,  indicates 
to  the  passengers  at  a  glance,  and  at  any  time,  their  exact 
position  during  a  cross-country  flight.  The  raised  posi- 
tion of  the  pilot  ensures  him  a  clear  outlook,  and  he  is 
ideally  situated  for  controlling  both  the  machine  and  mo- 


tors. The  two  270  horse-power  Rolls-Royce  motors  are  si- 
lenced as  effectually  as  is  the  engine  of  a  car.  The  use  of 
two  motors,  either  of  which  is  sufficient  when  running 
alone  to  maintain  the  machine  in  flight,  eliminates  almost 
entirely  the  risk  of  a  forced  landing.  The  machine  has  a 
speed  of  105  miles  an  hour,  and  will  fly  in  anything  up 
to  a  4.0-miles-an-hour  wind  in  perfect  safety,  and  without 
discomfort  to  the  passengers.  With  the  motors  throttled 
down,  an  easy  touring  speed  of  60  miles  an  hour  can  be 
maintained.  The  four-wheeled  chassis,  designed  on  mo- 
tor-car lines,  gives  a  maximum  of  strength  and  efficiency, 
and  is  fitted  with  special  brakes  which  bring  the  machine 
quickly  to  a  standstill  on  landing.  It  will  also  rise  from 
the  ground  after  only  a  very  short  run.  The  wings  fold 
back,  as  shown  below,  to  reduce  housing  space.  With 
wings  folded  the  span  is  reduced  from  60  feet  to  29  feet. 


The  Farman  "  Aerobus "  being  used  in  the  Paris-London  passenger  service.     Two  Salmson  engines  are  used.     Note  the  wing  end 

ailerons. 


SINCJl.K   MOTOHKl)   A  KK( )!'!.. \.\KS 


The  German  Gothas,   the  Aviatiks  and   the  Ago  biplanes 


Goths  G2 


THE    H.  and  M     FAR.MAN 


FIGHTING     AEROPLANE 


134 


SI.NU1.K   MOTOHKI)   AKKOl'I.AM  ^ 


Ii 
I     I 


Scale  drawing,  with  dimension',  in  niilimrtrr.,  of  the  Type  17  Nii-nport  M-out 

The  Nieuport  1%  Plane* 


An  immediate  step  in  the  transformation  from  the  mono- 
Jam-  to  the  biplane  is  formed  by  the  biplane  with  a  larger 
op  plane  and  a  smaller  bottom  plane.  This  type,  pro- 
Itici-il  liy  tin  N  import  firm  has  speed  and  ease  of  handling. 
I'hii-li  is  characteristie  of  the  monoplane,  and  stability  and 
liort  wing  span,  which  is  found  in  biplanes. 

Tin-  N  imports  may  be  divided  into  three  main  types  — 

Pyp<-  11,  a  single-seater  with  rectangular  body  up  to  the 

•nginc  cowl,  and  the  eowl  covering  the  upper  end  of  the 

notnr  only;  Tyjie  12,  which  is  a  two-seater,  having  its  V 

nti  rplane  struts  sloping  outward,  toward  the  top. 

!n  this  type  tin-  top  plane  has  a  fixed  center  section  and  i.s 

»vercd  with  transparent  Ccllon  sheets  to  give  a  better 

The  power  is  provided  by  a  110  h.p.  Clerget  en- 

tin. .     The  observer  sits  behind  the  pilot.     The  Type  17, 


of  which  we  give  here  a  line  drawing,  is  a  single-seater, 
with  a  circular  front  section,  and  some  of  this  tyjie  have  a 
spinner  over  the  propeller  boss.  The  general  arrange- 
ment resembles  that  of  the  Type  11. 

The  ailerons  are  mounted  on  steel  tubes,  inside  the  ring 
and  running  along  the  back  of  the  rear  spar  to  the  body. 
These  tubes  are  operated  from  the  control  lever  by  means 
of  cranks,  pull-and-push  rods  and  a  crank  lever.  The 
(•ranks  are  hollowed  out  to  provide  clearance  for  the  rear 
spar.  The  top  plane  has  slots  cut  in  it  for  the  cranks. 
The  pull  rods  are  connected  to  the  crank  lever  by  ball 
joints.  The  hand  lever  and  the  rudder  pedal  are  the  kind 
usually  used. 

The  top  of  the  rear  portion  of  the  body  is  covered  with 
curved  veneer.  The  tail  skid  is  supported  on  a  structure 


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The  Xieuport  scout  aeroplane  flown  by  American  airmen  in  France.     It  measures  only  15  meters  from  tip  to  tip,  and  is  driven  by 

a   Hit)  horse-power  Gnome  motor  and  a  French  propeller 


of  veneer   projecting   down    from   the   framework    of   the 
body. 

The  machine-gun  is  rigidly  mounted  over  the  center  of 
the  body,  directly  in  front  of  the  pilot. 

Herewith  are  the  dimensions  and  weights  of  one  of  the 
Nieuports: 

The  Type  n  Single  Sealer 

Span,  upper  plane   24  ft.  8  in. 

Span,  lower  plane   24  ft.  3  in. 

Chord,  upper  plane    3  ft.  11  in. 

Chord,   lower  plane    2  ft.  5  in. 

Overall   length    18  ft.  10  in. 

Height     8  ft.  1  in. 

Area,  upper  plane  with  ailerons   97  sq.  ft. 

Area,  lower  plane    49.5  sq.ft. 

Area,   rudder    ; 6  sq.ft. 

Area,  ailerons    14  sq.  ft. 

Area,  stabilizer   11  sq.  ft. 

Area,   elevators 14.5  sq.  ft. 

Stagger     2  ft.  3  in. 

Dihedral,   upper    179° 

Dihedral,    lower    174° 

Sweepback     170  degrees  30  min. 

Incidence,   upper    1  degree  30  min. 

Incidence,  lower   3° 

Power  plant   80  h.p.  Le   Khone 

Propeller,   diameter    8  ft.  2  in. 

List  of  Weights 

Upper  plane  with  fittings   79  Ibs. 

Lower  plane  with  fittings   33  Ibs. 

Tail    plane    7.7  Ibs. 

Elevators     9.5  Ibs. 

Rudder 6.6  Ibs. 

Body  with  engine,  complete   583  Ibs. 

Wire   stays    '. 7.7  Ibs. 

Wheels    22.4  Ibs. 

Interplane  struts    11  Ibs. 

Gross  weight,  empty   760  Ibs. 

Pilot     176  Ibs. 

Gasoline    (20y,   gallons)    121  Ibs. 

Oil    (5    gallons")     ..'. 44  Ibs. 

Machine  gun  and  ammunition   110  Ibs. 

Useful  load    451  Ibs. 

Total  weight,  loaded   1,210  Ibs. 

The  climb  in  4  minutes  is  3300  ft. ;  7  min.,  6600  f t. ;  11 


min.,  9900  ft;  16  min.,  13,200  feet.  The  lift  loading  o 
the  machine  per  sq.  ft.  equals  8.3  Ibs.,  and  the  power  load 
ing,  12.1  Ibs.  per  h.p. 

The  propeller  is  a  Levasseur,  of  2500  mm.  diameter  an< 
a  blade  width  of  270  mm. 

Comparative  table  of  the  three  above  mentioned  types 

Xo.  11  Xo.  12                Xo.  17 

Le  Rhone,  80  Clerget,     110    Le  Rhone,  11 

7,520mm.  9,200  mm. 

7,400  7,460 

1,200  1,820 

700  900 

13.65  sq.  m.  22.2  sq.  m. 


Motor 
Top  Span 
Bottom  Span 
Top  Chord 
Bottom  Chord 
Total   Area 
Incidence,  Top 


8,300  mm. 

7,800 

1,230 

730 

15.6    sq.    m. 


1  deg.  40  min.  2  deg.  30  min.  2  deg.  30  mir 


Incidence,    Bottom        3  degrees       3  deg.  30  min.       2  degrees 


View  of  the  forward  end  of  a  Xieuport,  showing  the  cowlin| 
completely  surrounding  the  motor,  which  distinguishes  thi 
Type  17 


Sl.\(;i.K   MOTOHKl)  AKHOl'I.ANKS 


i:J7 


ii|>orl   Scout   »itli  twin   l.rwis  guns  ami   lixnl    \'ickrrs  gun 


A   I'M-.   I  r,  i,rl,  Xiruport  S.-..iil  in  flight. 


\ import     Hipl.-me   rqtiipprd    with    a 
( 'Irrupt   motor 


Testing  out  a  120  h.p.  I.T  Rhdnr  motor  on 
I  '.  meter  Nieuport  ty|«-  J~.\ 


138  TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Side  view  of  the  Salmson  biplane,  equipped  with  the  Salinson  motor 


A  French  Salmson  biplane.    Two  seated,  it  is  used  for  artillery  observation  and  contact  patrol 


A    Salmson  biplane  with   a  250  h.p.   Salmson   stationary   radial    motor 


SI.M.I.K   MOTOR  Kl)  A  KRO1M.A  M  .S 


l.T.i 


III.    I  'rent  h  Spml  liiplunr  i-<|iii|>|>cd  with  Ilispiino-Snizii  motor 

The  Spad  Scout,  Type  S  VII 


is  type  of  plane  has  been  used  by  many  of  the  best 
Allied   a\  i  itors. 

.\pprii\iiii.-iti-  general  dimensions  of  the  S  VII  are  as 
follow  - 

Span,  uppi-r  pliine  (7.800  metres)  J.>  ft.  (i  in. 

Span,  lowt-r  plane  .'.">  ft.  li  in. 

Chord.  Inith  plane.  (1.4IHI  metres)  4  ft.  7  in. 

ll.-ip  Ix-twn-n  planes  (  l.-'.'.'i  meters)  4  ft.  -'  in. 

llvrrnll  length  (li.KHi  meters)  90  ft.  0  in. 

T»( n I  weight  ...  I/)-1.'.  Mis. 

I...-K!  47(1  lli>. 

I  Mini,  in  10  minutes  9,100  ft. 

Sperd  nt  sea  level  lit.'  m.p.li. 

t  :(.("»>  n*T>rs  I  .'h  m.p.li. 

•fltta  V  tjpe  Ilio  h.p. 

Both  pl.-itn  s  are  nearly  rectangular  in  plan,  the  i-nds 
U  in;;  si|ii  in  .-mil  not  rnkcd,  with  eorncrs  slightly  rounded 
off.  Tin  deep  eut-out  portion  of  the  top  plane,  over  the 
pilot's  seat,  as  well  as  the  elose  spaeing  of  the  intcrplane 
struts,  shows  a  large  area  of  plane  surface  aft  of  rear 
wiii£  In  .mis.  As  the  ailerons  arc  comparatively  narrow, 
nist  IK'  carried  on  a  subsidiary  wing  spar  located 
about  9  inches  back  of  the  main  beam. 

It  will  In-  iidtii-rii  that  tin-  iiiti-rpl.-iin-  bracing  is  iiiiiisu.-il  : 
'••s  from  each  side  of  the  fuselage  extend  directly  to 
i  struts,  crossing  at  the  intermediate  struts.  Where 
rea  i  ross  tin-re  is  a  steel  tube  brace  connecting  the 
.1  with  rear  intermediate  wing  struts. 


The  fuselage  is  exceptionally  deep,  and  the  bottom  is 
curved  In-low  the  lower  longerons  as  well  ax  the  sides  and 
top,  giving  a  smooth  streamline  effect.  The  fore  end  of 
the  machine,  which  house*  the  motor,  is  covered  with 
aluminum,  with  a  circular  radiator  opening  which  n  -.  m 
blcs  the  cowling  of  a  n>t.-iry  motor.  I'rotulioranccs  on 
cither  side  of  the  cowl  show  where  the  camshaft  covers 
of  the  Hisp.-ino  Sui/.-i  motor  project.  Perforations  are 
made  in  the  cowling,  about  the  motor  projections,  for  the 
admission  of  air. 

The  rudder  is  hinged  at  a  point  about  1<>  inches  Ix-yonil 
the  fuselage  termination.  The  usual  fixed  sUibilixing 
plane  and  elevators  are  employed.  The  vertical  fin  ex- 
tends 12  inches  forward  of  the  leading  edge  of  the  tail 
plane. 

Wheels  of  the  landing  gear  have  a  track  of  5  feet;  the 
axle  runs  in  slots  which  guide  it  up  and  backward  in  line 
with  the  rear  chassis  struts.  Shock  absorption  is  with 
rubber  cord. 

The  Hispano-Suiza  motor  develops  1GO  h.p.  at  about 
1500  r  p.m.  Eight  cylinders  arranged  V  type,  water- 
cooled,  four-cycle,  4.7245-inch  bore  by  5.1182-inch  stroke; 
piston  displacement,  718  cu.  in.  Wright,  including  car- 
buretor, magnetos,  starting  magneto,  crank  and  propeller 
hub,  but  without  radiator,  water  or  oil  and  without  ex- 
haust pipes.  4-15  Ibs.  Fuel  consumption,  one-half  pounds 
of  gas  per  horsepower  hour;  oil  consumption  three  quarts 
an  hour. 


140  TEXTBOOK  OF  APPLIED  AEK'    \V  \     '1C  ENGINEERING 


A  French  Spacl  biplane.     It  is  a  single  seater  and  Was  used   for  pursuit  work.     It  is  equipped   with  two  syn- 
chronized machine  guns  and  is  driven  by  a  Hispano-Suiza  motor  of  320  h.p. 


Rear  view  of  the  220  h.p.   Hispano-Suiza   Spad  biplane 


A   front   view   of  the   Spad   biplane.     Note   the   metal   interplane   struts,  the   "  Eclair "  propeller,  and   open  cowl. 


SIM       I 


W>KK1>   .\KUUIM..\\KS 


I  n 


Front   \irw   of  (hi-  Sp.ul  I  .111011  SIMJ,    .s.-.ilrr.      Knprir:   .'.'n  lip.   1 1  i-p.-uui  Sni/.i.      It   li  ••.  n  :t7  mm.    (1    inch)   cannon  khootiiifr  through 

UK-  hull  ul  tin    |irii|« Hi  i.  .uul  ..!-..  tun  lixnl  >\  uchronixeU  gun* 


Siilr    u 


Spud    Cniniii    Siiifrlr   Sealer.     ^.'0  h.p.    Ilispnno-Suizn   engini-.     '|'|M-  motor  N   completely  eiu-knrd    in   the  cowling. 
Tin-  excellent   >treainlinc  shape  of  the  fuselage  can  be  seen  from  the  photograph 


Spud  11-A3  Two  Seater.  Kn(rine:  »r»  h.p.  I  li-pmio -SuUa. 
I'M-I!  t.ir  ul -••rvalinn  pur|x»M^.  S|«eed  at  6i(K  leet:  II.'  luili--- 
per  hour.  Climh  to  |li,VK(  feet  In  :».'  tniiiute'i.  r'mliirnnce  at 
gronn.l  l.-v.-l:  J  hr-.  l.i  inin.  Arm.imrnt:  one  stationary  (fun 
ami  -'  flexihle  gunv  Crew:  one  pilot  and  one  oliM-n.-r. 
l-'ipiipiiH-nt:  Radio  iind  camera 


SKETCH  OF  BRISTOL  SCOUT 


WITH   Ls  RHONE  ENGINE 


£J 

mm 


<   CO 
?   Q 

i  < 

CL 


uj 


142 


SINCil.K   MOTOKKM   A  I  .!{<  )IM.A\  KS 


WITH  LeRHQME    C NO  INC 


Bristol  Scout— 80  Le  Rhone 


Tin-   Bristol  Scout  was  adopted  by  the  United  States 
Army  for  .•idv.inrrd  training  in   1918-19. 

ti  of  tli<-  Bristol  Sc-out  at  Wilbur  Wright  Field  gave 

th.    follow  in_-  results: 

.-d  (ft.)  M.p.h.  R.p.m. 

i,  .,  ,  I.... - 

MM  -'.  M15 


Cli.nl.    (ft.) 
10,000 


75 

Time 

1 1   ruin.     45  «rc. 
.M  miii.     .'«  nee. 


1.170 

Ratr   (ft.) 
tin 
240 


Srnirr  orllln^  (climb  100  ft.  per  m!n.)  13.000  ft. 

Wright,  rtnpty    7f»  MM. 

Total   ICMI!    2M  BM. 


Bri-tol  Scout  with  80  Lr 


Bristol  Scout   with  M  \JT  Kh6nr 


144 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


TOP  VIEW 


U5B-1    FIGHTER   WITH    3OO   H.P   HISPANO  -  SUIZA   ENGINE 


U.  S.  B.-l   British  Fighter 


300  Hispano-Suiza  U.  S.  Army  Tests 


Summary  of  Results  U.  S.  B-i 


Useful   load    

724  Ibs 

Fuel   and   oil    

.  .      344  Ibs. 

Total    weight    

3,910  Ibs. 

Pounds  per  sq.  ft.'  

.    .        7  05 

Pounds  per   h.p  

9  7 

Gasoline  consumption    

Oil  consumption    

g 

.  ," 

,llSJ 

Climb  (ft.)            Time                  R.p.m. 

Speed 

H.p.m. 

0 

114.5 

1,760 

6,000            5  min.     35  sec.           1,600 

113.fi 

1,700 

10,000           10  min.     45  sec.           1,600 

109.5 

1,660 

15,000          19  min.     30  sec.           1,600 

101 

1,600 

Theoretical  ceiling:   . 

.   25.000  ft. 

' 


U.  S.  B-l  with  300  Hispano-Si  iza 


SINCil.K   MOTOKKI)   A  KKO1M.A  M  .S 


FRONT    VIEW 


USB-I    FIGHTER   WITH   3OO  HP  HISPANO- 5UIZA  ENGINE 


I       S     ll-l    with  :«>0    Mi-|).n;i>-Si  i 


Marlin-yilc  Scout   with  :«KI   IlispiiiiD-Siiir.  i 


llrixt.,1   Smut    with  -i)   l.i-   Hhoni- 


ISrisl.il  So.ut   with 


146  TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


FRONT  VIEW 


U.5.B-B  FISHIER    WITH  E9D  H.R  LIBERTY  ENGINE 


U.  S.   15-.'  with  I.ilicrtv  "8' 


U.  S.  H--'  with  Liberty  "S" 


crz 


U.  S.  B-2  with  Liberty  "8" 


S.  B-2  with  I.ihi-rtv 


SIXiJI.K   MOIOHKI)   .\KK01M.  \\  I  ^ 


147 


Martln&yde  Smut  \vit 


M.irt.  ml   with  :VM>   1  Iis|>;iiici-Sui»» 


Martinsyde  Scout — 300  Hispano-Suiza 

Summary  of  Trials  (British) 

Duty  -  -  Fighting. 

Knginr         Ilispano-Sui/a.   .SO/i    h.p.,   at    1800   r.p.m. 

I'n.p.-llrr-     I). K. (i.l..  .V.J70.      Din..  -'7  IO.      Pitch,  2080 
(marked  i.      DI.I.,   U 

Military  load  —  281  11>- 

Total   Wright,   fully    Inadril  —  2289  Ibs. 

Ui -ight  |I»T  s<j.   ft.       (i.ii:.  Ibs. 

Weight  prr  h.p. —  7.5  Ibs. 

M.p.h. 

Sprr.l  at  10,000  ft H.'.:, 

Sp«-.-.l    at    l.J,(HX)    ft 136.5 


Greatest  In  iylit  n-aclird  —  24,700  ft.,  in  37  mins. 
Rate  of  climt>  at  this  height  —  1 10  ft.  •  mill. 
Air  i-inliir  inr.  .  almut  2'/4   ''rs.  at   full   speed  at    15,000 
ft.,  iiu-luiliiiir  climb  to  this  height. 


Anrroid 

II.,,.  I,  I 


Radiator  Temperature  Readings  on  Climb 


Atmox. 


K  nl 


Temp.  C.°     Temp.  C.'     AoiX 


Miu.  Sec. 

Climb    to    10,000    ft..        6  40 

Climb   to    15,000   ft..      II  45 

Climb   to   ->0,(K)0   ft..      19  40 


R.ofC.  in 

ft.   mill. 

1,176 

850 


R.p.m. 

I.-." 

1,795 


5,000 
IOJOOO 


IQflOO 


li 

7 
0 

_fl 
—  18 


-s 

n 
ra 

7:f 


77 
74 


Pos.  of 

K.p.m.  HlimU 

l.i,.l"  Oprn 

UlM  0|irn 

1,610  lip,  i, 

l.vi-,  i  |....  .1 
1^75 


I.8.S. 

70 
65 
60 


H.p.m. 
1,610 
I.  vi-, 
1,570 


SiT\icr   ri-ilinjr   (height  at  which   rate  of  climb  is    100 
ft.   min.)  —  a-l.-SOO    ft. 

Kstimatcd  absolute  ceiling  —  26,800  ft. 


Oil  Temperature  Readings  on  Climb 
Starting  with  nil  tank  full.     Castor  oil,  4  gallons. 
Aneroid  \tmnv  Oil  Kiipine      Oil  I'n-Mirr 

llriftht  Temp.C."    Temp.  C."     Trmp.  C.»     lb»./»q.  ft. 

(J.iMHt  6  60  74  75 

10,000  "  75  78  70 

H.OOO  —7  85  80  65 

16,000  —9  90  80  60 


TOP  VIEW 


U.5.  B-S  FIGHTER   WITH  B9D  RR  LIBERTY  ENGINE 


148 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


SEA  402.  Engine:  Lorraine  390  h.p.  Two  Seater  Pursuit  Biplane.  Speed  at  6500  ft.:  129  miles  per  hour.  Climb  to  17,000  ft. 
in  21  min.  Crew  and  armament:  Pilot  has  two  fixed  guns.  Gunner  has  two  flexible  guns.  Endurance  at  ground  consump- 
tion: 2  hrs.  30  min. 


Hunriot  Dupont  HD  3-C2.  Engine:  Salmson  270  h.p.  Two  Seater  Pursuit  Biplane.  Speed  at  6500  ft:  128  miles  per  hour. 
Climb  to  16,500  ft.  in  25  min.  Crew  and  armament:  One  pilot  with  two  fixed  guns.  One  gunner  with  twin  flexible  guns. 
Endurance  at  ground  consumption:  2%  hours. 


Side  view  of  the  Hanriot  Dupont  HD  3-C2  with  Salmson  270  h.p. 

motor 


Side  view  of  the  SKA  403  with  Lorraine  390  h.p.  motor 


tl 

* 


> 

-i 

? 


X 
•/ 


u 

X 


,1 


150 


SIN(;i.K   MOTORK1)  A  KKOl'l  ..\  \KS 


151 


1**" 


\nirricjin    S.    K.    .">    with    1s*  >    I  li-jniici  Sui/a 


The  English  S.  E.  5  Single-Seater  Fighter 


This  biplane  li.-is  i  surface  of  •'•t.H  si|iinrc  metres,  and 
both  |il:iiii-s.  connected  with  hut  our  pair  of  struts  to  each 
.sidr.  II.-IM-  a  span  of  K.l.'i  metres,  and  a  chord  of  1.5*2 
metres,  the  gap  I'niin  tin'  top  of  the  fuselage  amounting  to 
41.  ' :.  mrtrr. 

rrow  shape  prevails.  Tin-  V •  shape*  of  tin*  rqual- 
.si/.rd  rnds  of  the  upper  and  lower  planes  mounted  on  the 
centre  section  and  respective  body  rudiments  amounts  to 

1.7  I    tlejirei  |, 

The  siirlit  field  is  improved  hy  cutting  the  centre  section 
in  the  middle  and  the  lower  planes  near  the  body. 


.\lio\e  the  aniile  of  incidence  is  5  deg.  mean,  below  by 
the  hod\  li  dt  ir.,  by  the  struts  3  deg. 

Both    plnnc   .spars   show   sections   of   I    shape,   wl 
the  longerons  are  steel  tuln-s  of  1.7.5  millimetre  thicki 
and   1.5  mm.  outer  diameter. 

There  are  no  compression  struts  between  the  spars. 
MMMI  of  the  ril;s  being  solid  struts  instead. 

The  interior  wiring  of  the  planes  between  the  body  and 
the  struts  is  carried  out  in  simple  profile  wire,  that  of  the 
overhanging  ends  of  thick -ended  wire. 


5-£-5    PLANE   WITH  HISPANO-SUIZA   ENGINE 


152 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


TOP  1//EW 

S-E-5  PLANE   WITH  H/SPANO-SU/ZA  ENG/NE 


A  wood  strip  forms  the  back  edge  of  the  planes.  Fur- 
ther, two  auxiliary  ribs  ranging  from  the  leading  nose  edge 
to  the  main  spar  are  arranged  between  each  two  ribs. 

The  fabric  is  sewed  together  with  the  ribs,  and  is 
painted  yellow  below,  browned  above,  as  is  the  fabric  of 
the  body.  Shoe-eyes  are  arranged  on  the  underside  of  the 
trailing  edge  of  the  plane  to  assess  the  pressure. 

The  centre  section  struts  are  covered  steel  tubes.  The 
plane  spruce  struts  rest  in  long  stampings,  serving  as  fix- 
ing points  of  the  vertical  wiring. 

Profile  wire  is  employed  for  the  plane  cross  wiring 
with  twin  wires  for  those  carrying  load  and  single  for  the 
counter  ones. 

The  two  spars  of  the  upper  planes  are  strengthened 
further  between  the  centre  section  and  the  struts  with  two 
wires  each.  Unbalanced  ailerons  are  hinged  to  the  back 
crossbar  of  the  upper  and  lower  planes. 

The  body  shows  the  usual  strut  and  wire  combination, 
being  rounded  above  with  half-circle  frames  and  fairings, 
and  having  three-ply  wood  planking  of  4  millimetre  thick- 
ness to  the  pilot's  seat.  Fuselage  longitudinals  and  struts 
have  sections  of  I-shape,  except  the  vertical  struts  behind 
the  pilot's  seat,  which  are  worked  out  round. 

The  tail-plane  is  curved  to  both  sides  and  fixed  to  the 
body,  so  that  the  angle  of  incidence  can  be  varied  during 
the  flight  within  the  limits  +  4.5  deg.  and  —  3  deg.  To 
this  end  the  front  spar  is  turnable,  while  the  rear  spar, 


with  its  wiring,  is  fixed  to  a  tube,  arranged  shiftable  to  the 
body  stern  post.  This  tube  rests  with  a  piece  of  thread 
in  a  gear-nut,  again  resting  in  the  stern-post  fixed,  yet 
turnable. 

When  the  nut  is  turned  from  the  pilot's  seat  by  means 
of  wheel  and  cable,  the  tube  is  displaced  upwards  or 
downwards,  transferring  thereby  the  same  manoeuvre  on 
the  rear  spar  of  the  tail-plane,  and  thus  its  angle  of  inci- 
dence changes. 

The  elevator  hooked  to  the  fixed  tail-plane  partakes  in 
this  movement.  The  wires  for  operating  the  elevator  are 
led  through  the  body  and  tail-plane,  which  certainly  saves 
air  resistance,  yet  makes  twice  a  20  deg.  direction  change 
of  each  wire  necessary.  Main  and  tail-planes  are  equipped 
with  cellon  windows,  rendering  a  control  of  the  rollers 
possible. 

The  under-carriage  shows  the  normal  form.  The 
through-running  axle  rests  between  two  auxiliary  ones, 
There  is  no  limit  of  the  springing  range. 

The  tail  skid  shows  an  unusual  construction,  being  ar- 
ranged turnable  behind  the  stern  post  and  connected  with 
the  rudder  cable  by  intermediance  of  springs.  A  brass 
skid  bow  is  sprung  by  means  of  two  spiral  pressure  springs 
which  are  prevented  from  sideway  turning  by  inserted 
telescope  tubes. 

According  to  the  firm's  sign  board  the  Wolseley-His- 
pano-Suiza  engine  gave  the  30th  August,  1917,  on  brake 


SINCil.K    MOTOKKl)   A  I .!{(  MM    \  \  1   - 


1 :,:» 


.•mi  h.p.  •  -.MLS  I'.S.  .it  -.MIII.-,  revolutions.  Tin-  r.p.iu.  of 
tin-  fi>nr  hladi  d  airscrew  is  i;eirid  down  in  tin-  ratio  ot 
I-  to  .'I. 

'I'lir  exhaust  gas  is  li-cl  behind  tin-  pilot's  seat  in  two 
tulics  to  i-.-icli  siilr  ot  tin-  hodv  .  Tin-  motor  sits  so  that 

thi-rr  is   (fit    :i,-( -i  ssilulity  al'ti-r  removing  tin    li. ct.       The 

r/iili  itor  forms  tin    bow  of  tin-  I  odv  . 

A  i-oM-r  amm-emi-nt  makes  it  possible  t<>  uncover  the 
body  alioiit  halt  way  from  tin  pilot  s  - 

Tin-  main  prtrol  tank  of  IJH  litre-.'  capacity  is  | 
lu-hiiul  tin  motor  on  the  upprr  tusi-laii1'  longitudinals.  A 
gravity  tank  of  17  litres  capacity  is  arranged  in  the  centre 
section  between  the  li  ailiim  nl-t  .mil  the  main  spnr.  Tin- 
oil  tank  of  a  capacity  of  I  1  litres  lies  cross  in  the  engine 
frame  below  the  nar  eil^e  ot  tin  motor. 

The  fuel  sullices  Idr  a  (light  of  about  two  hours'  dura- 
tion. 

Following  instruments   are   -irmi^d   in   the   pilot's   seat: 

To  right:  A  ho\  for  the  light  pistols;  a  contact  breaker 
for  the  self  -starter ;  a  contact  breaker  for  tin-  two  mag- 
netos; a  triple  led  cock  for  the  gravity  ami  pressure  petrol; 
it  triple  led  cock  for  the  hand  and  motor  air  pump;  a 
thermometer  for  the  water  of  the  radiator;  the  petrol 
gauge  placed  on  the  hack  side  of  the  main  tank,  and  a 
m •inoiiicti  r  for  air  pressure. 

To  left:  das  lever;  lever  for  regulation  of  the  gas  in 
altitude  (lights;  lever  for  operating  the  radiator  Minds, 
clip  for  three  light  cartridges.  On  the  lottom  is  further 
arranged  a  hand  pump  for  the  hydraulic  machine-gun  gear; 
two  IIOM-S  tor  drums  for  the  movable  machine-gun  and  the 
sell  starter. 

A  .square  windshield  of  Triplex  glass  is  placed  in  front 
of  the  pilot's  seat.  li.  hind  it  a  box  is  arranged  in  a  queer 
position  to  the  body  with  access  from  outside. 

The  ti\ed  Vickcrs'  machine-gun  lies  to  left  of  the  pilot 
inside  tin-  hodv  fabric.  The  cartridge  girdle  is  of  metal. 
Tin-  tiring  of  the  machine-gun  takes  place  hydraulic-ally 


bv    mi-ana  of  a  control  arrangement,  placed  in  front  of  tin- 
motor  and  connected  with  tin-  in  >.  Inn.    -mi  through  a  cop 
per  main,  as  well  as  driven   from  tin    air  screw  bv  a  gear 
set.       The  firing  lever  sits  on  the  stick. 

On  the  bow  slnpi-d  iron  band  lying  on  the  centre  «ec- 
tion  rests  a  Lewis  gun.  which  can  In-  pulled  down  during 
the  Higlit  to  permit  vertical  tiring. 

The  empty  weight  of  the  a.  roplanc  was  worked  out  at 
TOO  kilos,  distributed  as  follows: 


Kilos. 

3.6 

il  o 


Knjrinr    

|-'.\li.nis|     e.illn-tiiili  

Self-starter     ....  

•;T       

Itiiiliiitnr   water    ...  

Air  screw    M.6 

Main    petrol    tank    17.H 

('•rnvity    |x-trol   tank                                   6.4 

Oil   tank    

Mut.ir    e<|iiipiiM-nt     6.4 

Bixly   with  M-at   ami   plate  rovers   141.0 

Tail  plate  iiiijile  of  im  iilener  ehaiiftr  arrangrmcnt   1.0 

I  'nder   carrinjfr    40.8 

T,,il    skid    3.7 

I'ilntiipr   arrangement    4.4 

Planes  with  wirimj  lli.3 

Vertical  and  horizontal  wiring  il.O 

HcMlv     equipment      " 14.0 


;,„.., 

The  fuel  weight  amounts  with  fully  loaded  tanks  to  1 1 1 
kilos,  so  that  the  total  useful  load  can  be  calculated  at 
250  kilos,  the  total  weight  working  thus  out  at  '.>:•><  kilos: 

9.16 
The   load   of   the   planes   is   thus:         — =12  kilos  per 


square  metre. 

The  performance  load  Is  then: 
horse-power. 


!.>  kilos  per 


Tail  plane  incidence  gear  of  the  S.  K. 


154 

' 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


^•^•••IBH^^HHIH  .          -  •  <•    i 

American    S.    E.    5    with    180    Hispano-Suiza 

S.   E.-5 — 180  Hispano-Suiza 

BRITISH  TRIALS 

The  American  machine  of  this  name  completed  its  tests 
under  U.  S.  army  supervision  in  1918. 

For  comparison,  the  summary  of  results  on  the  British 
and  American  S.E.-5  is-  given,  as  determined  at  Wilbui 
Wright  Field: 

Summary  of  Results  —  S.  E.-5  (British) 

Climb  (ft.)  Time  Rate  R.p.m.      Speed  R.p.m 

0  1,170  123  2,100 

6,500  6  min.     50  sec.          810  1.800         118.5  2.080 

10,000         11  min.    34  sec.         615         1,800         115.5  2,040 


American    S.    E.    5    with    ISO    Hispano-Suiza 

Climb  (ft.)                Time                Rate     R.p.m.      Speed  R.p.m. 

15,000         21   min.     20  sec.          340         1,800         10T.5  1,965 

20,000         50  min.     IT  sec.            60         1,780           85  1.S20 

Service    ceiling    19,400  ft 

Total    weight    2,051  Ibs 


Summary  of  Results  —  S.  E.-s  (American) 
Climb  (ft.)  Time  Rate     R.p.m.      Speed 


0 

6,500 
10,000 
15.000 
20,000 


8  min. 
13  min. 

22  min.     10  sec. 
£0  min.     30  sec. 


750 
590 
350 
140 


1.800 
J,800 
1.800 
1,790 


121.6 
120 
117 
109 
92.5 


R.p.m 
2,100 
2,140 
2,080 
2,000 
1,860 


Service  ceiling  (where  climb  is  100  ft.  per  min.) 20,400  ft 

Total   weight    2,060  Ibs 


A  squadron  of  British  aeroplanes,  type  S.  E.  5 


M\(;i.K    MOTOKKl)   AKK01M.. \.\KS 


-MM 


I         »...'.  i. •••  J\*  Stxaitli.'inelMn 

Jfinyxan  en  <7)>an>r i 
•f  !**•••  •  • 


I  — ,.  ..!••'•« 

J.      ^  »t  1*1  ••»  c«-«  *«< 

^Ii  x-x  *».«  *. 


«-*.r 


WlilllJ-lJ 


.      .4 


ft  V  »•«  "••" 


J,,<  ..  v  «».•  I 

-     • 


-WH- 


.'.  '»/«-«  »W «.../.- 


»»  X  ,"  - 


-36> 


w 


1 

I 

**     <0«O      *.-       •  •  •        tt 

*'«•/ 
>  ..,v..4.^. 

-     -.       .'..-.I 

Q»        >/-./. 
j       •*»•( 

».«>•'> 
*.**«' 

1 

I 

»* 

»      *.». 

•  • 

r.4  .  O  IS 

•!•'***»»•• 

'    «.  *       .       * 
*  .     .J*»  •  •  -» 

V.>>--- 

--*      .  -«*» 

*•**-.'•* 

/.*.'«.;»  •   j^-t-t 

r 


ini."-  "f  tin-  Supwith  Camel,  cquip|)f<l  with  1:10  h.p.  Clrrp-t  iiu)t»r 


A  flight  of  Sopwllh  "Camels"  over  a  British 


156 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Three  views  of  the  Sopwith  biplane  called 
the  "  1%  Strutter."  The  fuselage  is 
similar  to  that  of  the  triplane. 


The  British  Sopwith  Planes 

The  Sopwith  Aviation  Company  has  turned  out  several 
models  of  fighting  machines  which  have  proven  very  suc- 
cessful. One  of  the  best  known  types  is  called  the  "Pup  " 
and  possesses  very  great  speed.  It  is  a  two-seated  tractor 
and  is  frequently  referred  to  as  the  1  J/2  "  strutter."  Com- 
plete details  of  the  Sopwith  machines  are  not  available  at 
the  present  time. 

The  motors  used  are  the  Clerget,  Gnome,  Le  Rhone,  or 
Gnome-le-Rhone. 

The  Clerget  90  h.p.  motor  weighs  234  pounds,  has  seven 
cylinders  with  a  bore  of  120  mm.  and  a  stroke  of  160  mm. 
The  100  h.p.  motor  weighs  380  pounds,  has  nine  cylinders 
with  a  bore  of  120  mm.  and  a  stroke  of  160  mm. 

The  overhead  inlet  and  exhaust  valves  are  mechanically 
operated,  driven  independently  by  two  eccentrics  —  a  dis- 
tinctive feature;  one  crank,  single  and  dual  ignition,  alumi- 
num alloy  pistons.  The  crankshaft  serves  as  an  induction 
tube. 

The  Le  Rhone  motors  are  built  in  sizes  delivering  60, 
80,  110  and  150  h.p.  at  1200  r.p.m.  The  60  h.p.  has  seven 
cylinders,  with  a  bore  of  105  mm.  and  a  stroke  of  140  mm. 
It  weighs  199  pounds.  The  other  motors  have  nine  cylin- 
ders. The  80  h.p.  has  a  bore  and  stroke  of  105  x  140  mm. 
and  weighs  240  pounds;  110  h.p.,  bore  and  stroke  112x 
170,  weighs  308  pounds;  and  the  150  h.p.  bore  and  stroke 
124  x  180,  weighs  360  pounds. 

The  cylinders  are  turned  from  steel  and  fitted  with  cast 
iron  liners.  Cylinders  screwed  into  steel  crankcase.  Two 
valves  seating  in  cylinder  head;  induction  via  crankcase; 
shaft  to  crankease  and  two  valves  seating  in  cylinder  head ; 
induction  via  crankshaft  to  crankcase  and  by  external  cop- 
per pipe  to  cylinder  head.  Forced  lubrication.  Consumes 
.72  pints  of  fuel  and  .1  pint  oil  per  b.h.p. 

The  Gnome  100  h.p.  has  nine  cylinders;  bore  110  mm., 
stroke  150  mm.  Weighs  280  pounds.  Fuel  consumption 
nine  gallons  per  hour. 


The  Sopwith   "Camel" 

The  Sopwith  "  Camel  "  is  a  single-strutter  machiiu 
and  is  a  development  of  the  Sopwith  "  Pup,"  from  which, 
however,  it  differs  in  many  details,  apart  from  the  greatel 
power  of  its  engine. 

As  in  the  older  type,  the  wings  and  tail  plane  with  ele- 
vator are  of  trapezoidal  plan  form,  but  the  greatest  spai 
occurs  at  the  trailing  edge.  The  top  plane  centre-sectioj 
has  a  span  of  2.17  m.,  while  the  strut  attachments  are  onlj 
1.48  m.  apart.  As  the  petrol  pressure  tank  and  gravitj 
tank  are  placed  rather  far  aft,  the  pilot's  seat  is  placed 
immediately  behind  the  motor,  underneath  the  top  plane 
centre-section.  In  order  to  provide  a  better  view,  a  recfc 
angular  opening  is  cut  in  the  centre  section.  The  longa 
tudinal  edges  of  this  opening  are  provided  with  three-plj 
plates  projecting  beyond  the  wing  profile  so  as  to  reducj 
the  amount  of  air  flowing  over  the  edges.  To  facilitate 
getting  into  and  out  of  the  machine  the  trailing  edge  of  thj 
centre-section  has  been  cut  away.  Upper  and  lower  pland 
have  an  equal  span  of  8.57  m.,  and  an  equal  chord  of  1.31 
m.  The  aspect  ratio  is  therefore  6.25  against  the  aspi-ci 
ratio  of  5.15  of  the  older  type. 

The  wing  spars,  which  are  made  of  spruce,  are  spindled 
out  to  an  I  section,  with  the  exception  of  the  bottom  reaj 
spar,  which  is  left  solid.  The  gap  between  the  planes  h 
1.31  m.  at  the  tips  and  1.52  m.  near  the  body. 


SINC.I.K   MOTOUK1)   A  KK(  )IM..\\KS 


157 


British 

Avro 

Aeroplanes 

The   15rili-.li   Axrn  Company  has 

>eeii  prolific  in  its  production  of 
yp«'s.     Tin-      characteristics      of 

oinr    of    tlir    lati-st    t\  pi  -.    an-    re 
>rodticed   herewith   hy   courtesy   of 
It-rial  .li/t-    II  <•<•/.///. 

Mr.  A.  V.  Hoi  was  OIK-  of  the 
irst  aeronautic  engineers  to  pro- 
:  triplanc  which,  it  will  !«• 
ccallcd,  Mr.  Hoc  him-clf  Hew  at 
In-  historic  Ho-ton  I  I.-trv.ird  i\ii 
ion  in.  it  in  1'MO. 

It  will  !.<•  recalled  that  tin-  Hrit- 
sh  Secretary  of  State  for  the 
<oy.il  Air  I  orce.  speaking  at 
Manchester  on  December  20, 

IS,  said  of  the  Avro  training 
lachines  : 

It  was  uni(|ile  evidence  of  the 
icrtection  of  the  design  of  ... 
In-  A\  ro  that  to-day  it  had  bo- 
om, the  standard  tr.-iininj;  ma- 
hine  of  the  Hoy  a  I  Air  I-'orce  and 
huilt  in  larger  mimlxTs  than 
ny  otln-r  Aeroplane  in  the 
•orld." 


AVBO   S3 1 A 


Side  F.lcvatloni  of  Ib«  Awo  Machlntn. 


Table  of 

dimensions  of  Avro  machines. 

TV-TV  oi 

4                Wing 
0               «p»n. 

Vfmr 
chord. 

In.l,K 

rea               oct" 

leio*l        d«ncc. 

|j 

. 
I 

Dlhr.lr.il 

Am 

i 

\nt 

•  71™  *« 

nuKhm*- 

?. 

„• 

j 

S 

I 
1 

J 

_i 

3 

1 

I 

I 

i 

i  i 

1         1 

I 

o 

• 

1 

d. 
o 
t- 

i 

r     £l 

i-0 

Hi 

1 

'*'          0£ 

1 

ft.  in.    It.  in 

it.i  . 

It.  in. 

It.  in. 

,   i  i:  -    1 

n.               ' 

* 

II.  HI. 

ll.  in 

• 

si-U.     sji 

I1C  f  ITI 

|  urr  I.-.  1 

1Pff 

ll  11      16 

36 

1    10 

4  10 

171-5    15»*3 

})o*o      • 

•5 

3  6 

t     z 

>*3 

- 

43'  \     ;*>   o 

||*C 

44-0 

O-           90 

00 

JJO 

39     «      So 
18    6      )6 

60 
}6 

7    o 
5    • 

7    0 
S    6 

4i«*o    397*0 
182-0    164*0 

(115-0 
346*0      • 

'O 

*o 

7  3 
5  0 

0      O 

1     9 

i  J 
1-3 

• 
• 

-  .  . 

43*0 
13*8 

1JJ-0 
)2-  2 

17-       210 
4-        8-8 

13-  '. 

•)aoA 

n   i    04 

ft 

7     6 

7    6 

463-0     445*0 

910-0 

•o 

7    1 

o    o 

•• 

3*o 

\  ?1  '  f*     4s  •  4 

1°         245 

34  '  ) 

Sp-M-rr  " 
M,.o- 
cb*stcr  1 

B  •  9 

21 

6c 

6     0 

9      & 

t    6 
•    fi 

|6»-0       46.-0 

>08-0 

•o 

4    >l 

•    o 

| 

o-o 

Ji-o    13  j 

10-4 

2V6 

0           7  -t 

r'l 

Man- 

37     O      OO 

/     o 

7     w 

1  24  •  o    69*0 

38-0 

IO7-O 

16-       tS-o 

J4-0 

Chr«tn  11 

37    0     60 

60 

7    6 

7    6 

430*0     387*0 

817-0 

o 

7  j 

0      0 

• 

'•i 

- 

1*4-0     3O-O 

33-0 

83-0 

It-        16-9 

18-0 

3041 

31     I      3« 

36 

4  10 

4  10 

I7O*O     |6O*O 

J10-0 

•3 

3  » 

a     > 

| 

*'i 

43-5    -"--o 

TS-0 

44*0 

6*         90 

13-0 

SJIA 

20     6       1» 

27 

4    6 

4     6 

106  o    104*0 

210-0 

•$ 

4    1 

x    o 

• 

10 

19-1     I7-J 

II  -0 

J8-3 

O-          7-6 

7   S 

••Pojni'ai-" 

1     S       J5 

*5 

1      0 

4.    0 

*>t-o      Hj-o 

tlo-o     • 

M 

4   0 

1      4 

•• 

|*0 

27  0      •(  < 

•y 

:  •    » 

O    '1        ?     1 

•I    • 

Table  of  weights,  etc.,  and  performance 

Type  of 
machine 

Engine. 

Weight  of 
machine. 

1| 

u.  g. 
3 

&! 

Speed 
(m.p.h.). 

(  limb 
(in  mins  )  to 

I 

O 

f! 

f 

Load/h.p. 

P 

H.P 

K 

fl 

i 

'; 

It 

9 

| 

| 

| 

§ 

Type. 

. 

Q 

8* 

finuis 

6~ 

- 

it 

m  p  h. 

Ibs. 

Ibs. 

b» 

Rk«(5>3) 

Le  Rh. 

2  S. 

no 

1,230 
4.OOO 

1,823 
6.064 

3 

7 

225 

616 

9° 
97 

75 
88 

65 

a 

-5 
J 

16 
»7 

65 

35 
40 

5*52 
7*3 

16.5 
'5*9 

530*. 

H.S. 

200 

1.685 

2.680 

4 

432 

III 

108 

'. 

'4 

4°t 

18,000 

45 

8-23 

'3*4 

'M 

2-H  H.P. 

44<> 

4.361 

7.  '35 

5**5 

< 

56 

11*6 

106 

93 

7 

'7-3 

35< 

45 

7*75 

16.2 

1.2)0 

Spider(53i) 

C. 

130 

063 

'.5'7 

3 

330 

130 

no 

•i 

9-5 

22: 

19,000 

40 

7*78 

II.  6 

"5 

Manchester 

I 

2-D. 

640 

4.079 

6.586 

5-75 

700 

128 

122 

"5 

4 

; 

u 

4° 

:oooo 

45 

8*06 

10*3 

Manchester 

II 

2  P. 

600 

4.574 

7.1 

=,> 

3-75 

446 

'•15 

119 

I  I  : 

s 

6. 

- 

11.5 

43i 

17.000 

45 

8.  76 

»*9 

1.074) 

5041* 

C. 

130 

1,408 

2,006 

2 

160 

80 

65 

1 

. 

«»*5 

4° 

6.09 

18.1 

53'A 

C. 

130 

961 

l.5'4 

3 

330 

I2O 

i  to.  5 

103 

4) 

9  5 

22: 

19.000 

40 

7.22 

IT.  6 

Popular 

(534) 

G. 

35 

607 

5 

844-5J 

3*5 

•"7 

70 

67l 

621 

2O 

30 

•4  •  69* 

•>4  1.1 

I.e  Rh.  -  Le  Klione.           S.  - 

Sunbeam.          H 

S.  —  Hitpano    uixa 

C  -  Ckrgei.          D.  ^  "  .Dragonfly  "  A.B.C. 

P.  -  Siddcley  "  Puma.       G. 

-  Green. 

•  At  lo.ooo  ft.         < 

To  18.000.         J  To  15.000.         {  To 

1  7.000.         |  At  3.000.         f  At  5,000. 

THE  ITALIAN  5.V.A 

210  K>    SPA  MOTORED 

FIGHTING  5COUT 


CENTIMETIRS 


r  ,'. 


M'Laajblj; 


158 


SIXCLK   MOTOKK1)   AKKOl'l    \\KS 


l.V.t 


'I'hr  It  >li  in  >  V    \   I  ifilitiii):  Tractor  equipped  with  a  Spa  iOO  h.p.  engine  and  provided  with  two  Virkrrs  machine  jcun».     This  ma- 
•  him-  ran  clinil)  10,000  fret  in  H  ininiitcs  with  a  military  load  of  500  |M)iincls 

The  S.  V.  A.   Fighting  Scout 


The  S.  V.  A.  machines  arc  manufactured  by  Gio.  An- 

vildo  &  Co.,  of  (icnii;i.   Italy,  in  a  nunilicr  of  types  quite 

similar  to  one  another,  the  principal  differences  being  in 

In-  wing  spread  and  weight.      In  nearly  all  the  types,  the 

•inn-  |>ropi-lli-r,  motor  and  fuselage  is  used.     With  the  ex- 

eption  of  one  of  the  types,  the  interplane  strut  bracing  at 

itlu-r   side  of  the   body   is   arranged   in   the   form   of  the 

-ttrr  A'.     The  machine  is  convertible  for  water  use  by  re- 

l.'irinif  tin-  landing  gear  with  twin  floats,  as  illustrated  in 

lie  photographs. 

All  tin-  material  used  in  the  construction  of  these  MM 
hiiics  is  trsted  in  laboratories  before  being  installed,  and 
gain  rigidly  inspected  when  the  machine  has  been  tested 
ut  in  actual  flight.  The  woods  are  tested  for  transverse 
nd  longitudinal  tension  and  compression,  etc.  Cables  arc 
nun  .s  to  Id  times  as  strong  as  calculations  show  them  to 
*•  nri-i-ssary  under  extreme  conditions.  The  silk-linen 
o\ triii;;  is  somewhat  transparent  and  after  being  treated 
vith  dope  is  practically  untearable. 

Tin-  dimensions  given   below   accompany  the  drawing 
hown. 

General  Dimensions 

ipan.  upper  plane 9.100  mm.  (30  ft.  3  In.) 

ipan,  lower  plane   7,600  mm.  (25  ft.  0  in.) 

'honl,  both  planes   1,650  mm.  (5  ft.  5  In.) 

1,800  to  1,500  mm.   (5  ft.  II  in.  — 4  ft.  11   in.) 

Krrnll  lenjfth  H.100  mm.  (i6  ft.  7  in.) 

Her  .11   hei(fht    3^00  mm.  (10  ft.  6  In.) 

ft'eijrht,  emplj      640  kff.   (1.411    His.) 

ijrht,  loaded    900  kg.    (1.9S4  UPS.) 

Motor,   SI1  \    ilO   h.p. 

Maximum  speed   33-3  km.  (Hi  ml.)  p.h. 

Minimum  s|>eed   W  km.    (45  mi.)   p.h. 

iTHmh  in  14  min 4,000  met.-rs   (i :«,!.>:•  ft.) 

Main  Planes 

The  planes  are  in  four  sections.     The  top  plane  is  a 
tl.-it  span,  but  the  lower  plane  sections  are  set  at  a  dihedral 
Tin-   wing  curve  has  a   negative  tendency   at  the 


trailing  edge,  and  the  planes  are  given  but  a  slight  inci- 
dence angle  or  angle  of  attack.  As  in  most  of  the  fast 
Italian  machines,  the  trailing  edge  is  flexible,  tending  to 
flatten  out  the  wing  curve  as  the  speed  of  the  machine 
increases.  A  single  set  of  ailerons  are  hinged  to  the  upper 
plane. 

The  steel-tube  interplane  bracing  is  of  streamline  sec- 
tion, and  attachment  to  the  swing  spar  is  by  a  pin  running 
through  the  end  of  the  brace,  parallel  to  the  line  of  Might. 
The  bracing  method  employed  is  such  that  both  the  lift  and 
landing  stresses  are  taken  by  the  struts,  eliminating  the 
wire  bracing  cables.  Drift  and  anti-drift  cables  are  used 
in  the  usual  manner. 

Main  planes  have  a  surface  area  of  about  -tl.'2:>  sq.  m.; 
the  loading  of  the  machine  is  about  36,7<M>  kg.  (about  81 
pounds). 

Fuselage 

At  the  forward  end  of  the  fuselage,  the  motor  is  en- 
tirely covered  in.  and  the  cowling  runs  back  in  a  straight 
line  as  far  as  the  pilot's  seat.  The  rear  curves  of  the 
under  side  of  the  fuselage  are  composed  of  a  series  of 
straight  lines,  and  not  a  continuous  curve.  A  noticeable 
feature  of  the  fuselage  is  its  narrowness  in  the  vicinity 
of  the  tail  plane,  and  its  exceptional  depth  forward. 

The  interplane  struts  sloping  outward  from  the  fuselage 
are  not  connected  to  the  upper  longerons,  but  are  carried 
part  way  down  the  vertical  spacing  members  between  the 
up|wr  and  lower  longerons.  Evidently  a  compression 
member  is  located  at  such  points,  running  from  one  side 
of  the  fuselage  to  the  other. 

Veneer  is  used  for  covering  in  the  body,  except  at  the 
front  end,  where  the  aluminum  cowling  covers  the  en- 
gine. 

Tail  Group 

The  leading  edge  of  the  tail  plane  is  located  at  the  level 
of  the  center  of  propeller  thrust,  as  indicated  on  the  draw- 


160 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Official    photograph. 
View  of  the  body  assembling  and  covering  department  of  the  Ansaldo  factory,  one  of  the  largest  Italian  aeroplane  factories 


ing  by  the  dotted  and  dashed  line,  and  the  plane  is  fixed 
at  a  negative  or  depressing  angle.  It  will  be  noticed  on 
the  plan  view  of  accompanying  drawing  that  the  tail  plane, 
or  hori/.ontal  stabilizer,  is  exceptionally  small,  its  area 
l.eing  only  slightly  more  than  half  the  area  of  the  elevators 
or  tail  flaps.  The  flaps  are  worked  with  short  control 
tillers  located  close  to  the  body.  A  pair  of  steel  struts 
support  the  tail  from  the  fuselage. 

The  familiar  triangular  fin  OP  vertical  stabilizer  is  used, 
with  the  rudder  hinged  to  its  trailing  edge.  The  lower 
end  of  the  rudder  is  carried  in  a  cupped  metal  fitting  at- 
tached to  the  under  side  of  the  fuselage  termination. 

Control  wires  run  into  the  body  through  protective 
metallic  plates  with  friction-reducing  guides. 

Landing  Gear 

Steel  tube  chassis  members  carry  the  floating  axle,  cross 
wired  in  the  usual  manner.  The  shock  absorbing  rubber 
elastic  is  covered  in  to  reduce  skin  friction. 

The  tail  skid  is  unusual  inasmuch  as  it  relies  upon  a 
steel  leaf-spring  skid  for  its  shock-absorbing  effect.  The 
upper  end  of  the  spring  is  rigidly  clamped  to  a  metal  con- 
tainer, from  which  supports  are  run  to  the  upper  longerons 
of  the  body  and  to  the  tail  plane. 

Motor  Group 
The  engine  is  a  6  cylinder  SPA  developing  210  h.p.  at 


1600  revolutions  per  minute.  The  propeller  is  2750  m. 
(about  9  ft.  0  in.)  in  diameter,  with  a  2100  m.  (6  ft.  11 
in.)  pitch. 

Gasoline  is  carried  for  an  endurance  of  3  hours,  weigh- 
ing 105  kg.  (231.48  Ibs.)  and  oil  weighing  15  kg.  (3:!. 06 
Ibs.). 

General 

In  the  empty  machine,  the  weights  are  distributed  as  fol- 
lows: Machine  unequipped,  300  kg.  (661.38  Ibs.)  ;  motor, 
propeller  and  radiator,  315  kg.  (691.45  Ibs.);  fuel  tanks 
and  the  necessary  piping,  25  kg.  (55.11  Ibs.).  Total 
weight  610  kg.,  or  1410.95  Ibs. 

The  useful  load  consists  of  oil  and  gasoline  weighing 
120  kg.  (264.55  Ibs.)  and  an  additional  useful  weight  of 
140  kg.  (308.65  Ibs.).  The  loading  of  the  machine  per 
b.h.p.  is  equal  to  approximately  9  Ibs. 

This  type  of  S.V.A.  machine  is  also  manufactured  in 
what  is  called  the  "  reduced  size,"  in  which  the  wing  span 
is  shortened  to  7570  mm.  (24  ft.  10  in.)  but  otherwise  lire- 
serving  the  lines  of  the  "  Normal  "  type.  In  the  smaller 
machine,  the  total  weight  of  the  machine  is  875  kg. 
(1929.04  Ibs.)  instead  of  900  kg.,  and  the  loading  on  the 
surface  is  39.300  kg.  (87  Ibs.)  instead  of  81  Ibs.  as  in  the 
"  Normal  "  type.  With  the  smaller  machine,  the  same 
powered  motor,  and  a  change  in  the  angle  of  incidence  of 
the  planes,  a  much  greater  speed  is  obtained. 


SINCiLK   MOTOKKI)  A  KKOI'l  .  \  \  I •> 
The   Pomilio   Reconnaissance  Type  Tractor 


161 


I  •  ili  m    I'liniilin    ICi-i  otiiiaissance  ami    llomliarilmcnt    Arroplanr.      \pparatu-   i-  r.irrird  fur  thr  releitM1  of  honili-.  mill  n  movahle 

iiiafliiiir-^nii   h  iiiiiiuilfil  at   th«*  rrnr  ruckpit 


I:    \i.'w   <if  Ih<-   I'liinilii)   Aeroplane.     It  has  a  6-cylimler  KM)  h.p.   Fiat  cn(rfne  and  a   Fiat  marhinr-frun.     \\"nif  S|>MII. 
height,   l'-«"s  overall   li-ntflh,  30'-O" 


M-    l-oiinlio    Hrconn.nss,,,,-,-   and    Boml.anlmrnt    Tractor    «s    M-en    from    UK-    M.lr.     ()ffi.-ial    lrst>    |,a»e    shown    Ihi-    innrhine    to    Iw 
.hie  of  a  horizontal  speed  of  1*0  miles  an  hour.     Its  rlimh  is  also  very  good,  an  ascension  ..f 

.'.'  minutes 


162 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Gravity 
Tank 


A.E.G.  ARMOURED  AEROPLANE 

Span 4*'  6' 

Chord  S'  4* 

Gap V6' 

Tail  Plane  Span »'  o* 

Overall  Length      »3'  7f 

Engine   ("  Benz  ") *» 

Propeller- 'o7  3*  <lia 

Thickness  of  Armour       5 

Track  6"  ioi 


SI\(.1.K   MOTOHKI)  AKKOIM.ANKS 


The  A.  E.  G.  German  Armored  Biplane 


This  :u Toplanc  is  designed  f,.r  the  purpose  of  carrying  of  which  terminate  in  ball  ends  dropped  into  sockets,  and 

out    offensive    patrols   against    iiif.-intry.   and    i-,    furnished  there  bolted  in  position. 

with   armor,    which    affords    protection    for   its    personnel.  The  centre  section  contains  an  auxiliary  gravity  petrol 

This  armor  appears,  however,  to  be  more  or  less  expert-  Unk,  and  also  the  radiator,  ami  is,  therefore,  substantially 

mental.  braced  with  steel  tube  transverse  members. 

In  general   construction   it  closely   follows  the  lines  of  The   wings  are  set  with   a  dihedral   angle  of  approxi 

the  A.    I1'..  <•.  Twiii   Kngincd   Bomber,  though  the  arrange-  mately  6  dcg. 

incut  of  the  power  plant   is.  of  course,  entirely  different.  Tin-  aileron    framework   is  of  light   steel   tube  through- 

A  steel  tulnilar  construction  is  used  practically  through-  out,  the  tube  forming  the  trailing  edge  being  flattened  into 

*»it  an  elliptical  seetion.     The  ribs  are  fixed  by  welding.     The 

The  leading  particulars  of  the  machine  are  as  follows:  framework  of  the  ailerons  on  the  upper  wing  is  reinforced 

by  diagonal  bracing  of  light  tube. 

of  upper  wings  190.4  sq.  ft.  Tln-.se   are    of   light   steel    tube    streamline    in    section. 

of  lower  wings   ...  168     sq.  ft.  tapered  at  each  end,  and  terminating  in  a  socket   which 

Total  MM  of  «i,,^  ...  348.4  sq.  ft.  aDUts  against  a  ball-headed  pedestal  carried  on  the  wing 

\n  i  ot   up  lie  r  aileron   11.9  sq.  ft.  ,    .,  ,     .          .   .,      .     ..    . 

A  re.   of   lower   aileron    10      sq.   ft.  "P"1 5   thr°U«h   ll)e  8Ocket   »"d   the   bal1    »   P"**1  »   Sm«" 

Area  of  tail  plane  9.4  sq.  ft.  °o\i.     The   manner   in   which   this   attachment   is   carried 

Area  of  tin    7.6  sq.  ft.  out  is  exactly  similar  to  that  in  the  A.  K.  (i.  Bomber. 

Are  i  of  rudder  ...      6     sq.  ft.          The  whole  of  the  fuselage  is  built  up  of  steel  tubes 

Il,,ri/.,.nti.l   area  of  iMKly   .  48.6  sq.  ft  we,dcd  io^titfr   and  ,lavi        ,ffixed  at  their  junctions  aheet 

.Side   area  of  liodv    54.8  sq.  ft. 

(  r -,-tional  area  ,,f  Unly   14.4  sq.  ft.  steel  «V»  *"•«*  »«ve  as  the  anchorage  for  the  bracing 

.if  side  armor  33     sq.  ft.  wires.     The  diameter  of  the  longerons  and  of  the  frame 

Area  of  Imttuni  armor  29.4  sq.  ft.  verticals  is  20  mm.,  except  the  last  three  members  adja- 

.if  armor  bulkhead    10.4  *q.  ft  ^^  to  tne  tail,  of  which  the  diameter  is   16  mm.     The 

welding  throughout  the   fuselage  appears  to  be  of  very 

t  rew  —  pilot   ami   gunner    360  Ibs.  • 

Armament  —three  guns.  h'gn  quality.     The  longeron,  from  a  point  immediately  in 

Petrol  capacity   38  gallons  front  of  the  pilot's  cockpit  to  the  rear  of  the  gunner'* 

Oil  capacity    3  gallons  cockpit,  is  fitted  with  a  wooden  strip  taped  in  position. 

This  joint   shows   the   method    in   which   the  cross   brac- 

Tlie  manner  in  which  the  wings  are  constructed  is  ex-  ing  wires  are  furnished  with  an  anchorage.  In  one  or 
actly  as  shown  in  the  A.  E.  G.  Bomber  —  i.  e.,  the  spars  two  points  in  the  frame  construction  the  bracing  wire 
consist  of  two  steel  tubes  -10  mm.  in  diameter  by  0.75  mm.  lies  in  the  same  plane  as  the  transverse  tube,  and  to  allow 
thick.  At  their  ends  the  upper  and  lower  surfaces  of  for  this  a  diagonal  hole  is  drilled  through  the  tube,  and 
the  spars  are  chamfered  away,  and  flat  plates  welded  in  filled  in  with  a  small  steel  tube  welded  in  place. 
position,  so  as  to  provide  a  taper  within  the  washed-out  This  consists  of  a  triangulated  arrangement  of  steel 
portions  of  the  wing  tips.  The  wings  were,  unfortunately,  tubes  carrying  hollow  rectangular  section  steel  bearers,  on 
s.i  badly  damaged  that  no  accurate  drawing  of  their  sec-  which  the  crank  chamber  is  slung.  The  bearers  are  well 
tion  can  be  taken,  but  there  is  evidence  that  this  very  trussed  both  in  the  vertical  and  horizontal  planes,  and  are 
closely  follows  the  section  of  the  bomber,  which  has  al-  shown  in  dotted  lines  in  the  General  Arrangement  Draw- 
re-idy  been  published.  The  ribs  are  of  wood,  and  between  ings.  The  engine  bearers  themselves  are  2  mm.  in  thick- 
each  main  rim  is  placed  a  half-rib  joining  the  front  spar  ness,  and  have  an  approximate  sections  of  2  1/16  ins.  by 
to  the  semicircular  section  wooden  strip  which  forms  the  1 '  o  in. 

leading  edge.  The  wing  construction  is  strengthened  by  The  empennage  possesses  no  particular  points  of  in- 
two  light  steel  tubes  passing  through  the  ribs  close  be-  terest,  the  planes  having  the  usual  tabular  framework. 
hind  and  parallel  to  the  leading  spar,  which  are  used  for  The  tail  plane  is  not  fitted  with  any  trimming  gear,  but 
housing  the  aileron  control  wires.  The  bracing  against  a  method  of  adjustment  is  provided.  The  diagonal  struts 
dra-  consists  of  wires  and  transverse  steel  tubes  welded  which  proceed  from  the  base  of  the  fuselage  to  the  tail 
in  position.  At  the  inner  end  of  the  wings  special  rein-  plane  spar  arc  fitted  at  each  end  with  a  method  of  adj list- 
forced  ribs  of  light  gauge  steel  tube  are  provided.  The  ment,  allowing  them  to  be  extended  as  required  accord- 
spars  are  attached  to  the  fuselage  by  plain  pin  joinU.  ing  to  the  particular  socket  which  is  used  to  carry  the 

The  centre  section  of  the  upper  surface  is  constructed  leading  edge  of  the  tail  plane.      Neither  the  elevators  nor 

in  a  similar  manner  to  that  of  the  wings,  except  that  it  is  the   rudder  are   balanced.     The  rudder   post  is  mounted 

considerably  reinforced,  and  the  spars  are  larger  in  diam-  on  the  end  of  the  fuselage,  so  that  the  vertical  frame  tube 

etcr.     The  leading  spar  has  a  diameter  of  51  mm.  and  the  of  the  fin  is  very  stoutly  attached  to  the  frame  by  a  tri- 

rear  spar  45  mm.     The  centre  section  is  secured  to  the  angulated  foot 
fuselage  by  a  system  of  stream-lined  steel  struts,  the  feet 


GERMAN  AGO 

1917  TYPE  -230ffBENZ 

FIGHTING  5IPLANE 


J'cale  of  fee( 

'     i     1     i     i      i      \=r=c. 


104 


McLaujUiii  j 


SI.M.I.I.    MOTOHK1)   AKKUIM.ANKS 


Tin:  \<;<>  inn  \\i 

Tn|i:     Three-quarter      front      view.     Tin 
opening  in  tin-  top  pl.mr   for  thr   raili 
Jilur    mill    petrol    serxiee    tjnk    should    lie 
niiti-il.      Itnttiiiii:      \  i. •«•      fniiii      jili.ue. 
shoxunjr  in  ilin|!raiiiiiijitic  form  tin-  cnn 
slriictioii     of     top     plane.      IIIM-I:     The 
t.iil 


(The  German  Ago 
8  regards  its  general  lines,  tlic  Ago  is  of  a  striking 
unusual  appearance,  mainly,  no  doubt,  due  to  the  fact 
that  its  wings  are  tapered  very  pronoiitiredly  from  nmt 
to  tip.  This  is  very  unusual  in  any  modern,  and  when 
it  is  suddenly  met  with  in  a  German  machine  of  compara- 
tive  recent  date  —  from  various  marks  on  tin-  machine  one 
gathers  the  impression  that  it  was  built  certainly  no  longer 
ago  than  the  first  months  of  1917  —  the  question  that 
first  comes  to  mind  is  naturally  enough  related  to  the 
raiton  d'etre  of  this  uiiusu.-il  design. 

In  the  first  pl.-ice.  it  is  ohvious  that  whatever  it  was  the 

_ncr  was  aiming  at.  he  was  prcp.-ircd  to  go  to  consid- 
erable trouble  to  ohtain  it.  since  the  construction  of  sueh 

"••d  wings  as  those  of  this  Ago  are  not  by  any  means 

•n    attractive    proposition    commercially,    entailing,    as    it 

the  separate  construction  of  half  the   ribs,   no   two 

>  liieh  arc  alike  from  root  to  tip  in  one  wing.  Also 
M  the  spars  converge  to  a  point  at  the  tip.  they  intersect 
the  ribs  at  varying  distances  from  root  to  tip.  which  again 


\ 


Fighting  Biplane 

iiie.-iiis  extra  work  in  manufacture.  Ax  for  the  spars 
themselves,  (hex  also  taper  from  root  to  tip.  again  more 
trouble  and  expense. 

When  .standing  in  front  of  the  machine  one  is  at  once 
struck  by  the  peculiar  bracing  of  the  front  spar.  In- 
stead of  the  usual  interplane  strut  there  is  on  tin 
only  a  single  solid  wire  running  from  the  front  lower  spar 
to  the  front  top  spar,  while  no  lift  or  landing  cables  of 
any  sort  are  employed  Ix-tween  the  two  front  spars. 

This  feature,  then,  will  probably  IK-  found  to  contain 
(lie  solution  of  the  peculiar  design.  By  doing  away  with 
the  front  bracing,  a  much  freer  field  of  firing  is  obtained, 
and  there  can  be  little  doubt  that  this  was  the  object  for 
which  the  designer  was  striving. 

Owing  to  the  backward  slop,  of  the  leading  edge  of 
the  planes,  the  outer  inter-plane  struts  are  farther  back 
than  they  would  be  in  a  machine  with  straight  wings,  and 
also  owing  to  the  taper,  closer  together  and  therefore 
obstructing  the  field  to  a  smaller  extent.  The  narrower 


166 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Some  constructional  details  of  the  Ago  biplane.  1.  Dimensions  of  lower  front  spar 
near  body.  2.  Attachment  of  tubular  struts  to  fuselage  longerons.  3.  The  hardwood 
distance  piece  at  the  crossing  of  the  internal  wing-bracing  cables.  4.  Section  of  the 
lower  front  spar  at  the  point  of  attachment  of  the  interplane  wire.  5.  Perspective 
sketch  of  same  joint.  6.  Section  of  rear  spar.  7.  (A)  construction  of  false  spar  and 
aileron  leading  edge;  (B)  An  aileron  rib  (not  to  scale);  (C)  Aileron  crank  and  attach- 
ment of  inter-aileron  strut 


chord  near  the  tip  will  result  in  a  smaller  travel  of  the 
centre  of  pressure,  hence  possibly  the  twist  on  the  wings 
may  become  less,  and  the  absence  of  front  bracing  be  a 
less  serious  defect  than  one  is  inclined  to  imagine  at  first. 

When  we  say  absence  of  front  bracing,  this  is  not  quite 
correct,  since,  as  already  indicated,  a  single  solid  wire 
runs  from  top  to  bottom  front  spar.  As  is  well  known, 
in  biplanes,  with  top  and  bottom  planes  of  the  same  area, 
and  with  the  conventional  spacing  of  gap  about  equal  to 
chord,  the  top  plane  carries  about  30  per  cent,  more  load 
than  the  bottom  one,  or  roughly,  4/4  and  3/7  respectively. 
By  running  a  wire  from  the  top  to  the  bottom  front  spar, 
the  latter  is  therefore  made  to  carry  a  certain  share  of 
the  top  spar's  load,  thus  relieving,  to  a  certain  extent,  the 
enormous  bending  moment  that  must  be  present  on  a  com- 
paratively heavily  loaded  machine,  whose  front  spars  have 
a  distance  of  some  13  ft.  6  in.  between  supports. 

So  much  for  the  general  design  of  the  Ago.  As  regards 
the  construction  there  is  much  detail  work  that  is  inter- 
esting and  unusual.  The  fuselage  which  is,  as  in  the 
majority  of  German  aeroplanes,  of  very  roomy  propor- 
tions, as  regards  occupants'  accommodation,  is  covered 
with  fabric  except  the  front  around  the  engine,  which  is 


covered  in  the  three-ply.  The  floor  of  the  fuselage  is  of 
three-ply  from  the  stern  to  the  gunner's  (rear)  cockpit. 
From  there  to  the  nose  the  floor  is  three-ply,  covered 
with  aluminum.  In. section,  the  fuselage  is  rectangular, 
a  light  and  comparatively  flat  structure  forming  a  turtle 
back  over  the  top  of  the  main  fuselage  framework.  This 
turtle  back  is  built  up  as  a  separate  unit,  and  is  easily 
detachable  by  means  of  a  neat  and  very  simple  clip.  In 
case  of  severe  stresses  being  put  on  the  fuselage,  it  is 
therefore  an  easy  matter  to  detach  the  top  covering  and 
examine  and  adjust  the  internal  bracing. 

The  four  longerons,  which  are  of  square  section,  are 
pine,  from  the  rear  cockpit  to  the  stern,  while  in  front 
they  are  made  of  ash.  The  struts  are  in  the  form  of 
steel  tubes  and  the  solid  wire  bracing  is  attached  to  the 
struts  in  the  manner  shown  in  one  of  the  accompanying 
sketches.  A  small  socket  apparently  machined  out  of 
the  solid  steel  bar,  has  holes  drilled  in  its  edges,  through 
which  the  bracing  wires  pass.  This  socket  is  slipped 
over  the  end  of  the  tube,  which  has  small  dents  in  its 
end  to  give  more  room  for  the  loop  of  the  wire,  and  the 
socket,  with  its  strut,  is  secured  to  the  longeron  by  a  bolt 
passing  through  it,  with  the  nut  and  a  spring  washer  in- 


SIXCLK   MOTOKKI)   AKKO1M.AM   - 


KIT 


sitle  tin-  socket,  as  shown  in  section  in  mil-  of  our  sketches. 
Kxcept  for  the  fact  that  the  longeron*  arc  pierced  by  two 
lioles  —  the  horizontal  and  vertical  fuselage  struts  are 
.staggered  in  relation  to  one  another  —  close  to  one  an- 
other, this  arrangement  appears  to  !«•  \rr\  neat,  and  cer- 
tainly takes  up  very  little  space. 

In  front,  the  fuselage  bracing  is  in  the  form  of  diagonal 
steel  tubes,  no  wires  bciii'j  employed.  The  rear  eoekpit 
is  ivcupicd  li\  th<-  nrichinc  gunner,  who  is  seated  on  a 
small  seat  built  up  of  a  framework  of  steel  tubing,  over 
which  is  stretched  canvas.  This  seat  is  .so  hinged  and 
sprung  that  immediate  ly  the  gunner  stands  up  the  seat 
springs  into  a  vertical  position  out  of  his  way  in  case 
he  wishes  tu  <lo  his  shooting  in  a  standing  position.  When 
horizontal,  the  scat  is  supported  by  a  slanting  steel  tube, 
pivoted  at  its  lower  end  to  the  floor,  and  having  its  upper 
end  running  in  a  steel  guide,  bolted  to  the  under  side  of 
the  seat.  The  principle  will  be  better  understood  by 
reference  to  one  of  the  accompanying  sketches.  The  gun 
is  mounted  on  a  swiveling  bracket,  which,  in  turn,  is  sup- 
ported on  a  rotatahle  gun  ring  of  wood,  forming,  in  effect, 
a  turntable,  by  means  of  which  the  gun  may  be  traversed 
in  any  desired  direction.  To  prevent  damaging  the  nose 
of  the  machine  and  the  propeller,  a  stop  is  provided  for 
the  gun  in  the  form  of  two  small  frames  clipped  to  the 
rear  legs  of  the  cabane,  which  prevents  the  gun  barrel 
from  travelling  too  far  inboard. 

The  pilot's  seat,  which  is  in  the  front  cockpit,  is  placed 
on  top  of  the  main  petrol  tank  resting  on  the  floor  of  the 
fuselage.  A  service  petrol  tank  is  carried  in  and  mounted 
flush  with  the  top  plane  just  to  the  left  of  the  cabane. 
In  the  corresponding  opening  in  the  upper  right-hand 
wing,  is  carried  the  radiator,  and  in  connection  with  these 
two  it  is  interesting  to  note  that  the  water  and  petrol  is 
led  through  the  right  and  left  cabane  legs  respectively, 
thus  saving  a  certain  amount  of  piping,  which  would  other- 
wise be  exposed  to  the  air. 

The  controls  are  of  the  usual  German  type,  with  a  ver- 
tical lever  terminating  at  the  top  in  a  double  handled  grip, 
and  mounted  —  via  a  universal  joint  —  on  a  longitudinal 
rocking  shaft,  having  at  its  other  (rear)  end  crank  levers 
for  the  attachment  of  the  aileron  cables.  On  the  machine 
in  question,  no  guns  were  mounted,  but  from  the  various 
fittings  it  appeared  that  there  were  at  one  time  two  ma- 
chine-guns mounted  above  the  engine,  and  with  the  usual 
interrupting  gear  for  clearing  the  propeller  blades. 

The  large  engine  —  a  230  h.p.  Benz  —  is  mounted  on 
two  longitudinal  bearers,  which  are  in  turn  supported 
from  the  fuselage  by  three  direct  supports  —  at  the  rear 
a  sloping  panel  of  ply-wood,  in  the  middle  by  tubes  slop- 
ing up  from  the  junction  of  the  rear  panel  to  the  lower 
longerons,  and  at  the  front  by  another  panel  of  ply-wood, 
this  a  vertical  one.  In  addition  to  these  direct  supports, 
the  engine  mounting  is  further  braced  by  tubes  to  the 
upper  longerons,  and  by  diagonal  tubes  from  top  to  bot- 
tom longerons.  It  has  already  been  mentioned  that  the 
main  gasoline  tank  is  placed  on  the  floor  of  the  pilot's 
cockpit,  while  the  gasoline  service  tank  is  mounted  in  an 
opening  in  the  top  plane.  The  oil  tank,  which  is  com- 
paratively small,  is  carried  under  the  engine  housing  on 
the  right-hand  side  of  the  crank  chamber.  The  propeller, 
which  was  not  in  place  on  the  machine,  probably  had  a 


"spinner,"  or  hemispherical  MOS,  piece  over  the  boss,  as 
tins  would  appear  to  go  well  with  the  nose  of  the  fuse- 
lage, which  is  of  rounded  section  at  tins  point. 

The  main  planes  are,  as  already  indicated,  tapered  from 
root  to  tip  to  a  very  marked  extent,  the  trailing  edge 
sloping  considerably  more  than  the  leading  edge.  Suc- 
cessi\c  ribs  are  of  different  depth,  as  well  as  chord,  owing 
to  the  fact  that  the  spars,  in  addition  to  their  convergence, 
are  of  varying  depth  from  root  to  tip.  Whether,  how- 
ever, the  ribs  change  progressively  in  such  a  manner  that 
all  are  of  actually  the  same  sect  inn,  but  reduced  geomet- 
rically, or  whether  they  alter  in  shape  as  well  as  in  sise 
has  not  yet  been  ascertained,  but  judging  from  the  way 
in  which  the  spars  taper  it  would  appear  that  the  end  ribs 
are  not  of  quite  the  same  section  as  the  inner  onei. 

(  onstructionally,  the  ribs  are  of  the  usual  I  section, 
with  webs  which  appear  to  be  made  of  poplar,  and  with 
flanges  of  ash.  In  between  the  spars  the  webs  are  light- 
ened by  cutting  out  in  the  usual  way.  The  leading  edge 
is  of  pine  of  U,  or,  more  correctly  speaking,  of  a  rounded 
V  section  between  ribs,  but  left  solid  where  the  ribs  are 
attached  to  it.  The  trailing  edge  is  a  thin  lath  about  1 
in.  wide  by  about  3/16  in.  thick. 

The  main  wing  spars  are  of  an  interesting  construction, 
and  their  section  is  shown  in  the  accompanying  sketches. 
The  two  flanges  are  glued  to  thin  webs  (about  5  mm.), 
the  whole  being  wrapped  in  fabric.  No  tacks  or  screws 
are  employed  for  securing  the  webs  to  the  flanges,  the 
glueing  and  wrapping  being  apparently  relied  upon  to  be 
sufficient  for  the  purpose.  At  the  points  where  occur  the 
ribs  a  three-ply  distance  piece  is  glued  into  the  hollow 
spar,  but  so  narrow  is  this  that  in  several  places  it  was 
noticed  that  the  tacks  through  the  rib  flanges  had  pene- 
trated the  spar  flange,  missed  the  three-ply  distance  piece, 
and  had  its  end  projecting  inside  the  hollow  of  the  spar. 
The  rear  spar,  which  was  of  slightly  smaller  dimensions 
than  the  front  spar,  was  different  in  that  its  upper  flange 
had  been  spindled  out,  otherwise  the  two  spars  were 
similar,  also  in  that  in  both  the  top  flange  was  not  quite 
so  thin  as  the  bottom  flange.  The  spars  were  constructed 
of  what  appeared  to  be  some  kind  of  pine,  possibly  Unit 

Z'K- 

Where  the  bolt,  serving  as  an  anchorage  for  the  wire 
running  to  the  top  plane  occurred,  the  spar  was  strength- 
ened by  a  packing  piece  of  peculiar  form.  This  is  shown 
in  some  of  our  sketches,  which  will,  we  hope,  help  to  ex- 
plain it.  It  will  be  seen  that  the  saw  cuts  in  the  ends 
of  this  distance  piece,  leaves  four  tapering  ends,  which 
would  have  the  effect  of  cantilever  beams  proportioned 
to  carry  an  end  load,  the  latter  being  considered  as  the 
lateral  load  on  the  spar  at  this  point.  Whether  this. 
however,  was  in  the  designer's  mind  is  doubtful.  It  is 
more  probable  that  the  shape  of  the  piece  is  the  result 
of  an  attempt  at  stiffening  the  spar  for  a  considerable 
distance  on  each  side  of  the  joint,  without  carrying  too 
much  weight.  The  vertical  bolt,  to  which  reference  was 
made  above,  is  not  passed  through  the  spar  itself,  but 
through  an  additional  stiffening  piece  glued  to  the  front 
face  of  the  spar.  Two  horizontal  bolts  through  the  spar, 
securing  on  the  rear  face  of  the  spar  the  compression  strut 
for  the  internal  wing  bracing,  are  the  only  attachment, 
apart  from  the  glue,  of  this  vertical  packing  piece  to  the 


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spar  proper.  It  is  to  be  imagined  that  a  pull  on  the  inter- 
plane  wire  must  result  in  a  tendency  to  twist  the  spar, 
placed,  as  it  is,  so  far  from  the  vertical  neutral  axis  of  the 
spar.  Altogether  this  joint  impresses  one  as  being  very 
poorly  designed  indeed,  in  fact,  it  lias  the  appearance  of 
not  being  designed  at  all. 

The  outer  inter-plane  struts  are  stream-line  steel  tubes, 
with  a  diagonal  tube  welded  to  them  in  the  manner  shown 
in  the  illustrations.  In  addition  to  this  diagonal  tube 
there  is  a  wire  running  diagonally  in  the  opposite  direc- 
tion, probably  to  ensure  that  the  welded  joints  of  the 
struts  shall  not  have  to  work  in  tension  under  the  changes 
in  load,  caused  by  the  travel  of  the  centre  of  pressure. 

The  ailerons,  which  have  their  tips  at  a  slightly  smaller 
angle  of  incidence  than  that  of  the  inner  ends,  are  hinged 
to  a  false  spar  slightly  to  the  rear  of  the  rear  main  spar. 
The  section  of  this  false  spar  is  shown  in  one  of  our 
sketches.  The  leading  edge  of  the  aileron  is  in  the  form 
of  a  steel  tube,  partly  enclosing  which  —  and  at  some 
distance  from  it  —  is  a  strip  of  three-ply  wood,  the  ob- 
ject of  which  evidently  is  to  provide  the  requisite  depth 
of  the  leading  edge  of  the  aileron  without  going  to  the 
extra  weight  of  a  tube  of  sufficient  diameter.  The  method 
of  attaching  the  ribs  to  this  tube  is  also  indicated  in  the 
sketches.  A  short  strip  of  thin  steel  is  bent  around  the 
tube,  its  two  ends  projecting  back,  and  being  accommo- 
dated in  a  slot  in  the  rib.  This  strip  is  then  soldered 
(and  probably  pinned,  although  this  could  not  be  ascer- 
tained) to  the  tubular  leading  edge. 

Half-way  between  consecutive  ribs,  in  order  to  help  it 
retain  its  shape,  small  distance  pieces  are  tacked  to  the 
three-ply,  having  their  free  ends  abutting  on  the  surface 
of  the  tube.  Another  sketch  shows  the  tube  to  which  the 
inter-aileron  strut  is  attached.  The  crank  lever  of  the 
upper-aileron  is  a  somewhat  weird  and  complicated  affair, 
having  a  forward  projection  curving  up  over  the  false 
spar,  and  dipping  down  in  an  opening  between  two  ribs. 
To  this  projection  is  attached  one  of  the  aileron  control 
cables,  which  runs  over  a  pulley  in  the  lower  spar  and 
internally  in  the  lower  wing  to  the  cranks  on  the  longi- 


tudinal rocking  shaft.  In  plan  view  the  aileron  crank 
lever  is  bent  and  runs  through  a  rib,  the  clip  attaching 
it  to  the  inter-aileron  strut  being  similar  to  that  of  the 
lower  aileron  shown  in  the  sketch.  From  this  aileron 
crank,  a  cable  passes  over  another  pulley  in  the  same 
casing  as  that  of  the  first,  and  hence  through  the  lower 
plane  to  the  controls.  It  will  thus  be  seen  that  both  ele- 
vating and  depressing  the  aileron  is  a  positive  movement. 

The  tubular  leading  edge  of  the  ailerons  is  supported 
by  a  small  bearing  at  the  inner  end,  and  by  two  clips  of 
steel  bent  over  the  tube  and  bolted  to  the  false  spar  at 
certain  intervals.  Thus  each  aileron  is  carried  in  three 
bearings.  The  outer  end  of  the  leading  edge  of  the 
aileron  is  free.  A  fact  which  at  once  impresses  itself  on 
one  in  looking  at  the  lateral  control  of  the  Ago  is  that 
the  point  from  which  the  aileron  is  actuated  is  very  near 
its  inner  end,  leaving  a  very  large  amount  of  the  aileron 
area  outside,  a  fact  which  must  give  rise  to  considerable 
twisting  stresses. 

The  tail  planes  are  of  similar  construction  as  that  of 
the  main  planes,  the  same  form  of  box  spars  being  em- 
ployed. The  stabilizing  plane  is  brought  to  the  same 
level  as  the  top  of  the  fuselage,  by  dropping  the  lower 
longerons,  somewhat  after  the  fashion  of  the  old  Deper- 
dussin  monoplanes.  A  clip  secures  the  front  spar  of 
the  tail  plane  to  the  longerons,  while  the  rear  spar  is 
attached  by  means  of  a  sliding  clip  arrangement,  which 
allows  (not  during  flight)  of  adjusting  the  angle  of  inci- 
dence of  the  tail.  The  vertical  fin,  which  is  of  tubular 
construction,  is  mounted  on  and  moves  with  the  tail  plane. 
\o  very  great  amount  of  adjustment  is  therefore  pos- 
sible, as  a  comparatively  small  movement  of  the  rear  spar 
of  the  tail  plane  brings  the  rudder  against  the  edge  of 
the  cut  out  portion  of  the  fin.  (See  illustration.)  The 
rudder,  which  is  also  built  of  steel  tubes,  has  no  support 
above  the  stern  of  the  body,  this  being  difficult  to  obtain 
in  conjunction  with  the  adjustable  fin.  The  result  is 
that  the  rudder  is  very  much  overhung  and  does  not  look 
any  too  strong  for  its  work. 


THE  AGO  BIPLANE 

1.  The  gunner's  seat.  2.  The  rear  cabane.  3.  A  cable  attachment  extensively  employed.  The  cup-shaped  socket  is  machined 
out  of  the  solid  and  has  a  slot  through  which  passes  the  shank  of  the  turnbuckle.  Three-ply  packing  is  placed  between  the  plate  of 
the  fitting  and  the  base  so  as  to  make  up  the  thickness  of  the  socket.  4.  The  gasoline  service  tank  lying  on  its  end  on  the  floor. 
When  in  place  on  the  machine  it  is  carried  in  the  opening  in  the  upper  wing,  to  the  left  of  the  cabane. 


SINC.I.K   MOTUUKl)  .\KU01M.A.\KS 


Hi!  I 


AREA    OF 
TAIL.   PLANE. 
FT. 


FIGHTtR 
TYPE    CV. 

S.S.O/-P.  M£RC£DfS. 


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TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Three  views  o  '  the  Albatros  "  CV 
Fighter.  (Description  supplied  by  tli 
British  Air  Mhiit-try.) 


The  Albatros  Type  "CV"  Fighter 


This  Albatros  biplane  belongs  to  the  "  C  "  class  —  that 
is,  a  general  utility  machine  used  for  artillery  observa- 
tion, reconnaissance  work,  photography  and  fighting. 
The  machine  .  na  also  used  for  bombing  —  in  a  small 
way  only  —  as  it  is  equipped  with  a  bomb  rack  holding 
four  bombs. 

Aerodynamically  the  Albatros  to  be  dealt  with  in  what 
follows  is,  perhaps,  chiefly  interesting  on  account  of  the 
evident  attempt  on  the  part  of  the  designer  to  provide 
as  good  a  streamline  body  as  is  possible  having  regard  to 
such  external  fitments  as  machine-guns,  etc.,  which  nat- 
urally detract  to  a  certain  extent  from  the  efficiency  of 
the  lines  of  a  body  of  a  modern  two-seater,  where  the 
gunner  frequently  has  to  stand  up,  with  the  upper  por- 
tion of  his  body  projecting  above  the  fuselage  covering. 
This  effort  at  streamlining  is  particularly  noticeable  in  the 
nose  of  the  machine,  where  the  aluminium  cowling  over  the 
engine  is  carried  right  across,  leaving  only  the  exhaust 
collector  exposed.  In  front  of  the  covering  of  the  body 
proper  is  a  cowl  shaped  as  a  truncated  cone,  which  serves 
to  enclose  the  nose  and  reduction  gear  of  the  engine,  and 
to  carry  the  lines  of  the  body  into  those  of  the  "  spinner  " 
around  the  boss  of  the  air  screw.  The  sides  of  the  body, 
from  a  short  distance  behind  this  cowl  to  the  tail,  are  flat, 
as  is  also  the  bottom,  but  the  top  of  the  fuselage  is  covered 
with  a  curved  covering  of  three-ply. 

At   the    rear    the    fuselage   terminates    in    a    horizontal 


knife's  edge,  an  easy  flow  being  provided  for  the  air  by 
running  the  top  covering  of  the  fuselage  into  the  three-ply 
covering  of  the  fin  in  a  smooth  curve.  Similarly,  the 
fixed  tail  plane,  which  is  of  a  symmetrical  section  and 
very  deep,  has  its  top  surface  practically  in  continuation 
of  the  top  covering  of  the  body,  presenting  no  great  and 
abrupt  changes  in  curvature.  The  total  effect  is  one  of 
extremely  smootli  and  easy  flowing  curves,  and  the  body 
resistance  cannot  be  very  great  in  proportion  to  the  cross 
sectional  area  of  the  body.  We  have  no  figures  of  the 
actual  resistance  coefficient  in  the  formula  R  =  k  AV2, 
but  are  inclined  to  imagine  that  the  coefficient  k  has  quite 
a  low  value. 

Constructionally  the  Albatros  shows  much  that  is  of 
interest,  chiefly  in  the  construction  of  the  body.  Funda- 
mentally, the  Albatros  body  construction  is  that  employed 
in  building  light  boats  and  hydroplanes.  There  is  a  light 
framework,  consisting  of  four  main  rails  at  the  corners 
of  the  rectangular  section  body,  two  auxiliary  rails  some- 
where about  half-way  up  on  the  sides,  and  bulkheads  or 
transverse  partitions  of  varying  shape  and  thickness  along 
the  body  at  intervals.  The  whole  is  then,  as  in  boat  build- 
ing, covered  with  a  skin  of  veneer  ply-wood,  in  this  case 
three-ply.  Regarded  as  a  compromise,  this  form  of  body 
construction  would  appear  to  be  quite  good.  Without  en- 
tailing the  time  and  expense  of  the  true  monocoque  body, 
it  provides  a  reasonably  good  streamline  form.  As  a 


SINCLK   MOTOKK1)  A  KKOl'I.A  M-.S 


171 


manufacturing  proposition  it  is  probably  about  equal  to 
tin-  girder  type  of  fuselage,  wliili-  it  has  the  advantage 
of  not  requiring  any  truing  up  in  tin-  erecting  process, 
tliis  follow  ing  automatically  when  making  the  parts  over 
j  igs  am!  foriniTs.  One  advantage  this  form  of  boily  does 
appear  to  possess,  although  to  a  somewhat  li-sser  extent 
than  tin-  trui-  inonocoquc  shell  splinters  and  rifle  anil 
niaehine -ifun  bullets  are  less  likely  to  damage  it  seriously 
than  is  the  ease  with  the  girder  type.  In  the  latter,  should 
a  longeron  be  shot  through  nearly  all  the  strength  of  the 
structure  is  yone.  whereas  this  si  mi  monocoquc  structure 
would  retain  its  strength  e\en  alter  dama^in^;  some  of  the 
longitudinal  members. 

Finally,  there  is  the  ijiiestion  of  strength  for  weight. 
Hesults  of  a  test  i;i\e  the  factor  of  .safety  of  the  Albatros 
body  as  about  (id.  and  the  resistance  to  bending  •.;..">  times 
greater  than  that  of  a  diagonally  wired  fuselage  of  the 
same  outside  dimensions,  and  having  members  of  the  sire 
usuallv  employed  in  structures  of  this  type.  The  landing 
resistance  nl  the  Miner  type  of  body  appeared  to  be 
greater  than  that  of  a  cross  wired  fuselage  of  the  same 
weight,  although  no  actual  figures  were  given  showing 
how  much  greater. 

When  looking  into  the  detail  construction  of  the  Alba- 
tros body  the  first  thing  that  impresses  one,  apart  from 
the  absence  of  internal  cross  bracing,  is  the  extensive  use 
that  has  been  made  of  veneer  in  the  construction  of  the 


tratist  erse  bulkheads  or  formers,  which  take  the  place  of 
the  struts  and  cross  members  of  the  girder  type  of  Univ. 
In  Fig.  1  are  shown  the  different  bulkheads  of  the  body, 
with  dimensions,  etc.  The  rail  half-way  up  the  sides  of 
the  body  is  placed  parallel  with  the  propeller  shaft,  thus 
serving  as  a  datum  line  from  which  to  make  measurements 
of  distances  and  angles. 

In  order  to  better  form  a  conception  of  the  Alb.it ros 
construction  we  have  shown,  in  Fig.  1,  half-sections  of  the 
more  important  and  representative  bulkheads.  In  the 
front  portion  of  the  Itody  the  bulkheads,  which  here  have 
to  take  the  weight  of  the  engine,  are  about  I  '  (  in.  thick, 
and  are  made  up  of  a  number  of  laminations  of  wood, 
which  are,  of  course,  so  placed  in  relation  to  one  mother, 
that  the  grains  of  adjacent  layers  run  at  angles  to  one 
another. 

Fig.  •„'  sin. MS  the  nose  of  the  Albatros,  and  clearly  in- 
dicates the  method  of  supporting  the  engine.  The  first 
bulkhead,  it  will  be  seen,  is  solid,  and  in  at  right  angles 
to  the  propeller  shaft.  The  second  bulkhead  —  2,  Fig. 
I  — is  lightened  by  piercing  as  shown,  and  is  also  vertical, 
while  the  third  engine  .support  is  formed  by  a  solid  bulk- 
head —  3,  Fig.  1  - —  which  slo|>cs  back  no  us  to  support 
the  front  chassis  struts  and  front  cabane  .struts  at  its 
lower  and  upper  ends  respectively.  As  the  front  engine 
support  is  clearly  shown  in  the  sketch.  Fig.  •„'.  it  has  not 
hi  en  included  in  Fig.  1.  The  bulkhead  numbered  1  in 


rtlon.  of  torn*  of  tb*  mora  imponul   bulkh. 
of  tb*  Albttro,  n«htin»  blpUux. 


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Fig.  1  is  merely  a  former,  and  does  not  help  to  support 
the  engine  bearers.  These  are  of  I-section  spruce,  and 
have  plywood  flanges  top  and  bottom  as  shown  in  Fig.  3. 
The  upper  flange  is  continued  outwards  to  the  middle 
longeron  so  as  to  form  a  shelf  or  bracket  at  the  sides  of  the 
engine. 

A  construction  somewhat  different  to  that  of  the  engine 
supports  is  employed  in  the  panel  between  the  pilot's  and 
gunner's  cockpits.  This  consists  (4,  Fig.  1)  of  a  spruce 
framework  faced  each  side  with  3  mm.  three-ply,  the 
whole  having  a  thickness  of  26  mm.  (about  1  in.).  Be- 
hind the  gunner's  cockpit  is  a  light  partition  built  up  as 
shown  in  5,  Fig.  1.  Two  light  spruce  struts  run  diagon- 
ally across  from  corner  to  corner  of  the  bod}',  crossing  in 
the  center  of  the  fuselage  at  which  point  they  are  rein- 
forced by  three-ply  facings  and  triangular  blocks  glued 
into  the  corners. 

Their  attachment  to  the  upper  and  lower  body  longerons 
is  of  a  similar  construction,  and  will  be  clear  from  the 
diagram.  On  their  front  faces  these  diagonal  struts  are 
provided  with  a  2  mm.  flange  to  stiffen  them  against 
buckling.  A  canvas  curtain  is  secured  to  the  front  of  this 
partition,  having  in  it  pockets  for  maps,  etc. 

From  this  point  back  to  the  front  where  the  tail  plane 
and  vertical  fin  are  attached  the  formers  of  the  body  are 
in  the  nature  of  a  very  light  framework  of  thin  struts, 
a  typical  one  being  shown  in  6,  Fig.  1.  The  general  con- 
struction and  some  of  the  dimensions  of  the  various  mem- 
bers will  be  clear  from  the  illustration. 

One  of  the  features  in  which  the  present  Albatros  dif- 
fers from  previous  types  is  the  construction  and  attach- 
ment of  the  tail  plane  and  vertical  fin.  The  latter  is  cov- 
ered with  three-ply,  and  is  made  integral  with  the  body, 
out  of  which  it  grows,  so  to  speak.  The  construction  is 
shown  in  7  and  8,  Fig.  1,  and  in  the  perspective  sketch, 
Fig.  4.  The  tail  skid  is  supported  on  one  and  sprung 
from  the  other  of  these  two  bulkheads,  as  illustrated  in 


Fig.  5  (below),  the  general  and  detail  construction 
of  it  being  evident  from  the  sketches.  The  tail  plane 
is  provided  with  hollow  spars  which  fit  over  cantilever 
beams  integral  with  bulkheads  7  and  8,  Fig.  1,  the  details 
of  which  arrangement  will  be  dealt  with  later. 

Having  dealt  with  the  bulkheads  or  transverse  parti- 
tions of  the  Albatros  fuselage,  the  longitudinals  rails  will 
be  considered  next.  These  are  of  a  somewhat  compli- 
cated nature,  varying  as  they  do  along  their  entire  length, 
not  only  as  regards  being  tapered  from  front  to  rear,  but 
also  in  the  different  form  of  spindling  out  employed  at 
the  various  points,  and  in  the  method  of  reinforcing  with 
other  strips  of  wood,  partly  in  order  to  increase  their 
strength  where  required  and  partly  to  make  their  overall 
section  conform  to  the  various  angles  and  curvatures  of 
the  outside  three-ply  covering  of  the  fuselage. 

From  Fig.  6  a  fairly  good  idea  may  be  formed  of  the 
shape  and  dimensions  of  the  longerons  at  various  points. 
The  lower  one  (left  hand)  is  originally  of  rectangular 
section,  but  is  lightened  from  point  to  point  by  various 
forms  of  spindling  and  stop-chamfering.  Thus  at  the 
point  B  (see  key,  diagram  Fig.  6),  the  inner  face  of  the 
bottom  longeron  is  spindled  out  on  its  inner  face  with  a 
curved  cutter.  At  other  points  of  this  longeron  farther 
towards  the  stern  various  sections  are  met  with,  as  chan- 
nel, solid  rectangle,  and  L  sections  of  various  proportions. 
Between  the  horizontal  stern  post  and  the  point  at  which 
the  middle  longeron  meets  the  lower  one,  the  latter  is  re- 
inforced with  a  triangular  section  strip,  so  as  to  carrv  the 
three-ply  covering  into  the  sloping  side.  Similarly  at  the 
section  A,  Fig.  6,  the  longeron,  which  is  here  of  solid 
rectangular  section,  is  reinforced  on  the  outer  side  with 
a  curved  trip,  spindled  out  externally,  and  with  a  smaller 
strip  on  the  lower  face  of  the  longeron. 

The  upper  longeron,  which  is  originally  of  rectangular 
section,  is  spindled  out  to  channel  and  L  sections  at  va- 
rious points,  as  shown  in  X,  Y,  Z,  Fig.  6.  So  as  to  form 


Fig.  5 — The  tail 
skid  and  its  at- 
tachment on  the 
Albatros  biplane. 


SINCil.K    MOIOHK1)   AKUOI'I    \\|   - 


Fig.  2.— Sketch 
showing  engine 
bearers  of  the 
Albatros  biplane. 


Fig.  3 Section     of 

the    engine    bearer* 

of       the       Albatros 

biplane. 


Fig.  4— Con- 
struction of  toe 
vertical  fin 


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fiitir 


g"(F       g General    arrangement  of  the  Albatros  body.      Side  elevation  and  plan  to  scale. 


an  attachment  for  the  curved  top  of  the  body,  the  top 
longerons  have  glued  to  their  upper  face  additional  strips 
of  triangular  section  while  at  the  point  Y,  Fig.  6,  the  sec- 
tion is  left  rectangular  so  as  to  form  a  support  for  the 
gun  ring.  In  addition  to  their  function  as  strengthening 
members  these  strips  serve  the  further  purpose  of  pre- 
venting the  bulkheads  from  sliding  along  the  longerons, 
as  they  are  cut  off  where  a  bulkhead  occurs,  against  the 
front  and  rear  sides  of  which  they  abut.  In  some  places, 
as  for  instance  in  the  front  of  the  body  where  the  cover- 
ing is  in  the  form  of  an  aluminium  cowl  over  the  engine, 
the  strips  are  omitted  and  the  cowl  attached  to  turn-but- 
tons as  shown  in  the  sketch  Fig.  1.  At  such  points  the 
bulkheads  are  prevented  from  sliding  along  the  longerons 


by  a  long  wood  screw  passing  horizontally  through  the 
longeron  into  the  bulkhead. 

The  middle  longerons,  which,  as  already  pointed  oul 
in  a  previous  article,  are  horizontal,  i.  e.,  parallel  to  the 
propeller  shaft,  are  of  smaller  overall  dimensions  than  are 
the  four  main  longerons.  They  are  rectangular  section 
lightened  in  places  by  stop-chamfering,  as  shown  in  a  and 
b,  Fig.  6. 

Fig.  8  shows,  in  side  elevation  and  plan,  the  genera 
arrangement  of  the  fuselage,  and  should,  in  conjunctioi 
with  the  various  sections  and  key  diagrams,  explain  fairlj 
clearly  the  general  layout  of  the  body.  Where  the  tai 
begins  two  extra  longerons  on  each  side  have  been  buill 
into  the  bulkheads  of  the  body.  These  two  short  longer 


FiJ.  9.— Sketches  of  the  tall  plane  and  its 
attachments  oh  the  Albatros  biplane. 


SIN(;i.K   MOTOKK1)  A  Kl«  >1M  A  \  I  - 


17.-. 


ons  have,  in  |)l.-in.  a  direction  parallel  tn  tin-  lint-  of  Hight, 
while  tin  in.-iin  longerons  continue  cm  their  converging 
course.  Tliis  arrangement  is  indicated  in  tin-  plan  view 
K.  In  side  elevation  tin-  short  longerons,  against 
which  lie  the  inner  ril>s  of  tin-  tail  plane,  have  the  same 
ciir\ature  a-  the  tail  plane.  In  this  manner  the  lines 
of  the  rear  part  of  the  body  are  not  spoiled,  while  an  easy 
flowing  eur\e  is  prox  ided  for  running  the  tail  plane  into 
the  bodv  . 

Keferenee  lias  already  been  made  to  the  peculiar  attach- 
ment of  the  tail  planes  to  the  body.  The  sketch  at  the 
top  of  l-ig.  !'  shows  in  perspective  this  attachment,  which 
is  also  illustrated  in  the  diagram  in  the  Imttoni  left-hand 
corner  of  Fig.  •>.  The  bulkheads  of  tin  body  are  extended 
outwards  tn  form  cantilever  heanis  which  support  the  tail 
plane.  There  are  three  of  these  cantilever  beams,  while 
further  support  is  provided  for  the  tail  plane  leading  and 
trailing  edges  as  indicated  in  the  sketches.  The  .spars  of 
the  tail  plain-  are  of  the  box  tvpe.  built  up  of  ash  flanges 
with  thin  three-ply  sides,  eut  out  for  lightness.  These 
spars  an  s,i  proportioned  that  they  rit  over  the  cantilever 
beams,  which  do  not.  it  will  be  seen,  run  right  out  to 
the  edge  of  the  tail  plane,  but  are  finished  off  just  outside 
the  second  tail  plane  rib.  No  external  braeing  of  the  tail 
pi  me  is  provided,  the  depth  of  it  and  the  method  of  mount- 
ing being  relied  on  for  the  necessary  strength. 

To  pro\  idc  against  the  tail  plane  sliding  off  its  canti- 
lever supports  it  is  secured  at  the  leading  and  trailing 
•  due.  The  former  attachment  is  indicated  in  the  bottom 
right-hand  corner  of  Fig.  9.  A  sheet  steel  shoe  fits  over 
tin  corner  of  the  leading  edge  and  inner  rib,  and  through 
this  shoe  a  long  bolt  passes,  which  runs  across  the  body  to 
a  similar  shoe  on  the  other  side.  In  Fig.  10  is  shown  the 
rear  attachment  of  the  tail  plane.  A  sheet  steel  box  sur- 
rounds the  corner  of  the  fuselage.  Welded  to  this  box  is 


a  short  tnlx-  which  tits  into  n  circular  recesi  in  the  end  of 
the  tr.iiling  edge  of  the  tail  plain-.  As  tin-  elevator  tulx- 
runs  right  across  and  is  fitted  with  collars  Ix-aring  against 
the  sides  of  the  clips  that  form  the  Itcaring  for  the  elevator 
tube,  the  trailing  . -dgc  of  the  tail  plane  is  prevented  from 
slipping  outwards. 

The  manner  employed  of  forming  bearings  for  the  >  I. 
vator  is  indicated  in  the  diagrams  of  Fig.  1O.  A  steel  strip 
is  Ix-nt  over  the  tube,  and  its  two  free  ends  are  Ix-nt  over 
and  tit  into  slots  in  the  trailing  edge  of  the  tail  plane. 
Each  clip  is  tin  n  secured  to  the  tail  plane  by  a  vertical 
bolt  as  shown  in  the  diagram.  The  trailing  edge  of  tin- 
tail  plane  is  spindled  out  to  a  si-mi  circular  section  as 
shown,  and  a  curved  metal  distance  piece  is  screwed  to 
this  trailing  edge  or  spar,  so  an  to  form  tin  second  half 
of  the  bearing  of  which  the  bent  steel  strip  forms  the 
other  half.  To  remove  the  elevator  the  bolts  securing  the 
clips  are  undone;  the  clips  are  then  bent  outwards  until 
their  free  ends  clear  the  slots,  when  the  elevator  can  be 
removed  bodily. 

As  the  elevator  i.s  built  of  steel  tubing  throughout,  wood 
I'hi.  ks  of  the  shape  shown  in  detail  I,  Fig.  10,  are  em- 
ployed for  attaching  the  fabric  covering.  These  blocks 
span  over  the  steel  strip  bearings,  and  are  secured  to  the 
tubular  leading  edge  of  the  elevator  by  screws  as  shown 
in  section  Ml!.  A  hole  in  the  opposite  wall  of  the  tube 
serves  for  the  insertion  of  the  screwdriver. 

As  regards  the  remaining  details  of  the  tail  of  the  Alba 
tros  little  need  be  said,  as  they  are  fairly  evident  from  the 
plan  and  sections  of  Fig.  11.  It  will  suffice  to  point  out 
a  rather  ingenious  construction  of  the  leading  edge  of  the 
tail  plane.  In  plan  the  tail  plane,  it  will  be  seen,  is 
roughly  semi-circular,  and  its  leading  edge  therefore  has 
to  be  shaped  to  this  curvature.  As  an  ordinary  strip  of 
.solid  spruce  spindled  out  to  a  semi-circular  section  would 


Flft.  10.— DcUiK  of  the  tail  plane  and 
elevator  attachment  on -the  Albatro* 


ST£EL  CLIP 
\  x-~-'Lx 


JeerntM  A  .A 


DETAIL/. 


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ALBATROS 
TAIL    PLANE 


Fig.  11.— General  arrangement  and  dimensions  of  the  members  of  the  tail  plane  on  the  Alb*tro«  biplane. 


scarcely  be  strong  enough  for  this  work,  a  different  method 
has  been  employed.  It  appears  that  originally  the  lead- 
ing edge  of  the  tail  is  made  up  of  four  laminations  of  ash, 
having,  of  course,  their  grains  running  in  slightly  different 
directions.  The  rectangular  section  spar  thus  formed  is 
then  spindled  out  to  a  semi-circular  section,  as  shown  in 
the  diagram,  leaving  the  impression  that  the  leading  edge 
is  made  up  of  seven  thin  strips  of  wood  glued  together. 
The  resulting  leading  edge  appears  to  be  one  of  great 
strength,  while  at  the  same  time  being  quite  light. 

The  cockpits  of  the  Albatros  are  arranged  in  the  fash- 
ion now  universally  adopted  for  two  sealers,  by  Allies  as 
well  as  by  the  enemy,  i.  e.,  the  pilot  in  front  and  the  gun- 
ner in  the  rear  cockpit.  The  pilot's  seat  is  mounted,  in 
the  Albatros,  on  the  main  fuel  tank,  which  has  two  an- 
nexes on  top,  one  on  each  side  of  the  seat.  This  arrange- 
ment is  clearly  indicated  in  Fig.  12,  in  which  the  small 
clips  preventing  the  seat  from  sliding  about  on  the  tank 
will  be  noticed.  The  filled  cap  is  mounted  on  a  tubular 
projection  extending  through  the  fuselage  covering,  thus 
enabling  the  tank  to  be  refilled  from  the  outside.  A 
smaller  auxiliary  tank  is  mounted  above  and  to  the  rear 
of  the  main  tank,  in  the  gunner's  cockpit,  as  a  matter  of 
fact.  Botli  tanks  are  connected  up  to  a  by-pass  or  dis- 
tributor, so  that  both  or  either  tank  can  be  connected  up 
to  the  engine,  two  pumps  being  provided  for  maintaining 
the  necessary  pressure,  one  driven  by  the  engine  and  the 
other  hand  operated.  Thus,  whatever  tank  is  being  used, 
petrol  is  fed  to  the  carburetor  under  pressure.  This  has 
probably  been  a  necessary  provision,  as  the  tanks  are 
placed  relatively  low  and  gravity  feed  would,  therefore, 
be  apt  to  be  unreliable  when  the  machine  is  climbing  at  a 
fairly  steep  angle. 

Constructionally  the  petrol  tanks  are  of  interest  in  that 
they  have  been  internally  braced  by  rods  running  across 
from  side  to  side,  the  attachment  of  the  rods  being  visible 


Eiifi 


on  the  outside  of  the  tank  as  shown  in  Fig.  12.  To  pre- 
vent the  petrol  from  slushing  about  inside  when  the  tank 
is  nearly  empty  baffle  plates  are  fitted  dividing  the  main 
tank  longitudinally  into  five  compartments,  communicating 
with  each  other  through  the  circular  openings  shown  in 
the  section  of  the  tank,  Fig.  12.  As  the  supply  pipe 
leaves  the  tank  fairly  high  up  —  it  can  be  seen  on  the 
front  right-hand  side  of  the  tank  in  Fig.  12  —  it  is  carried 
down  inside  to  the  bottom  of  the  tank  so  as  to  enable  the 
last  drop  of  petrol  to  be  forced  out  and  into  the  carbu- 
retor. The  main  tank  is  mounted  on  brackets  as  shown 
in  one  of  the  sketches,  and  is  secured  by  metal  straps  hav- 
ing an  arrangement  for  adjustment. 

In  Fig.  13  is  shown  the  general  arrangement  of  the 
controls.  There  is  a  transverse  rocking  shaft  at  each 
end  of  which  are  mounted  crank  levers  for  operating  the 
elevators,  while  in  the  centre,  pivoted  so  as  to  be  free  to 
rock  laterally,  is  mounted  the  main  control  lever. 
Mounted  on  the  transverse  shaft,  but  not  moving  with  it, 
is  another  lever,  which  operates  the  claw  brake  mounted 
on  the  wheel  axle.  The  arrangement  of  this  brake  is 
shown  in  Fig.  14.  By  pulling  the  lever  the  free  end  of 
the  claw  brake  is  pulled  upwards,  thus  causing  the  claw 
to  dig  into  the  ground.  On  releasing  the  lever,  the  brake 
is  returned  to  its  normal  position  by  the  action  of  the 
spring  shown  in  the  sketch. 

The  transverse  rocking  shaft  is  carried,  as  indicated  in 
Fig.  14,  in  two  bearings  mounted  on  the  lower  longerons. 
A  forward  and  backward  movement  of  the  control  lever 
causes  the  shaft  to  oscillate,  and  with  it  the  two  crank 
levers  to  which  are  attached  the  elevator  control  cable. 


SI\(;i,K   MOTOKKI)   AKUOl'l.  \\  l.s 


177 


Tin -sr  cables  run  from  (lit-  crunk  lever,  around  a  pulley 
slightly  forward  of  the  transverse  -.halt  a-,  shown  in  the 
sketch,  anil  hence  to  tin-  top  crank  ICMT  on  tile  elevator. 
Tin-  return  calilc  runs  from  the  crank  on  tin  under  side 
nt  tile  elevator  to  tile  crank  on  the  transverse  shaft.  Kn 
route  these  cables  pass  over  pulleys  Iiloiilited  in  the  rear 
position  of  the  fuselage,  these  pulleys  hcina  shown  ill 
detail  in  sunn  of  the  accompany  ing  sketches  (Fig.  15). 

As  regards  literal  control,  the  general  arrangement  of 
this  is  indicated  in  diagrammatic-  form  in  Fig.  16.  From 
the  control  lever  the  direct  cahlc  passes  over  a  pulley  on 
the  transM-rse  shaft,  along  through  the  lx)ttom  wing, 
around  another  pulley  in  the  wing,  and  hence  to  the  rear 
half  of  the  aileron  crank  le\er.  The  return  ealile  runs 
from  the  front  half  of  the  aileron  crank  lever,  around 
.•mother  pulley  in  the  lower  wing,  through  the  wing  and 
through  the  transverse  shaft  to  a  pulley  on  the  other  side 
of  tin'  control  lever,  and  hence  to  the  screw  on  the  con- 
trol lever.  The  details  will  he  clear  from  Fig.  13. 

The  foot  l>ar  operating  the  rudder  is  mounted  on  a  pyra- 
mid of  steel  tulies,  and  the  rudder  cables  arc  taken,  not, 
it  will  In  seen,  from  the  foot  bar  itself  as  is  generally 
done,  hut  from  a  short  lever  projecting  forward  at  right 
angles  to  (he  foot  har.  From  this  lever  the  cables  pass 
over  pulleys  and  to  the  cranks  on  the  rudder.  It  will  be 
seen  that  provision  has  been  made  for  making  adjustments 
of  the  loot  bar  to  suit  pilots  of  different  height  by  fitting 
on  extra  foot  bar. 

As  in  the  majority  of  German  machines,  provision  has 
1'ei  n  made  for  locking  the  control  lever  in  any  position 


either  Hying  level,  climbing,  or  descending.  This  is  ac- 
complished ly  means  of  a  collar  free  to  slide  along  tin 
control  column,  but  U  m-  split  and  provided  with  a  bolt 
for  tightening  up.  when  the  collar  is  locked  in  position 
on  the  control  column.  Anchored  to  this  collar  by  two 
screws  is  a  fork  end.  from  which  a  tnU  runs  dou  n  and 
forward  to  terminate  in  a  ball  rind  socket  joint  secured  to 
the  bottom  of  the  fuselage.  This  ball  and  socket  joint, 
it  will  In-  set  n.  enables  the  control  column  to  be  moved 
freely  in  any  direction,  and  to  allow  it  to  I*-  moved 
from  side  to  side,  even  when  the  forward  movement  of 
the  column  is  prevented  by  locking  the  collar.  In  this 
manner,  the  pilot  can  lock  the  elevator,  while  operating 
the  control  column  from  side  to  side  for  lateral  control 
with  his  knees. 

While  on  the  subject  of  controls,  reference  might  IM- 
made  to  the  crank  levers  on  the  elevator  and  rudder. 
These  are  shown  in  Fig.  17,  from  which  their  construc- 
tion will  be  evident.  The  crank  lever  of  the  elevator  has 
projecting  from  it  a  tapering  tube  running  to  the  trailing 
edge  of  the  elevator.  The  tubular  rudder  post  is  working 
in  bearings  similar  to  those  described  in  our  last  issue 
when  dealing  with  the  hinges  for  the  elevator.  At  the 
bottom  the  rudder  tube  fits  into  and  is  supported  by  a 
socket  carried  on  a  clip  bolted  to  one  of  the  transverse 
bulkheads  of  the  fuselage.  A  peculiarity  characteristic 
of  the  Albatros  is  the  method  of  attaching  the  control  ca- 
bles to  the  crank  levers.  A  socket  is  formed  in  the  end 
of  the  crank  lever,  and  into  this  fits  a  cup- shaped  piece 
of  steel  machined  on  one  of  the  bolts  of  the  wire  strain,  r*. 


Fig.  14 Dlaftr»mmatic 

«k«tcb  of  the  claw  br»k« 
on  tb«  AJb»tro«. 


Ki(r.  l:t.  Tin-  controls  of  I  In-  Ailmtros  liiplnnr.  Inset*  show  the  hnll  anil  socket  joint 
for  thr  control  l.-v.-r  locking  arrangement,  and  hand  grip  with  pin  trigger  on  the  main 
control  lever. 


Fig.  16.     Diagram  of  the  aileron  control  system  of  the  Albatros  Fighter 


Fig.  15.  "  A  "  shows  the  pulley  over 
which  the  elevator  cable  passes  after 
leaving  crank  lever  on  rocking  shaft  (See 
Fig.  13).  "B"  The  pulley  mounted  on 
the  top  longeron  (in  front  of  the  tail 
plane)  over  which  the  elevator  control 
passes.  "C"  This  pulley  bolted  to  the 
middle  longeron  just  ahead  of  the  tail 
plane  guides  the  elevator  cable.  "  D " 
This  pulley  guides  the  rudder  cable  in 
front  of  the  footbar. 


Fig.  18.  The  machine-gun  and  its 
mounting  on  the  Albatros  Fighter.  The 
bag  for  the  spent  cartridges  should  be 
noted.  When  not  in  use,  the  butt  of  the 
gun  rests  in  the  clip  shown.  The  two 
smaller  sketches  show  the  locking  devices 
for  the  gun  pivot  (left)  and  the  gun 
ring  (right) 


Fig.  19.  So  as  to  be  out  of  the  way 
when  the  gunner  is  firing  from  a  stand- 
ing position,  the  seat  on  the  Albatros 
Fighter  is  hinged  and  sprung  as  shown 
in  this  sketch 


Fig.  17.     Elevator  and  rudder  crank  levers  on  the  Albatros  biplane.     (A)   Elevator  crank  lever  with  its  ball  socket  joint  for  the 
turnbuckle.     (K)   Bottom  rudder  bracket  and  crank  lever.     (C,"\    Mounting  nf  HIP  rmlHcr 


SIM.l.l.    MOTOKKD   AI.KOl'L. \.\KS 


IT'.t 


t-'if.  ii.  Shrrt  strrl  s|uir  IHIX  and 
socket  fur  compression  tulw  i>f  the  up- 
|MT  pl.im-  of  tin-  Mli.-itrus  liipl.mi-  I  In- 
Uittniii  skrtch  shows  the  ;itt.-i.  liim-nt  of 
the  terminals  for  the  Interplane  cnMcs 
ami  struts 


=  ctlons    ..I    Hi      leading   edge,    in 'in    spurs    nnd    false   spar  of  the    AHwtros 

liiplime 


nuu-li  in  tin-  same  manner  .-IN  the  terminal  attachment  of 
tin  main  lift  cables.  Thus  any  vibration  in  the  <oiitr.il 
cable  is  not  transmitted  to  the  crank  lever,  the  cup-sha|>cd 

•f   tin-   turn-buckle   bolt   being  free   to   move   in    it* 
sin  k.  t  in  tin-  crank  lever. 

n  nee  has  already  been  made  to  one  part  of  the 
armament  of  the  Alliatros.  namely,  the  s\  nchroni/.ed  ma- 
chin,  -mi  op.  rated  by  the  pilot  from  the  trigger  on  the 
main  control  column.  In  addition  there  is  a  movable  ma 
elnni  i;un  mounted  on  the  usual  gun  ring  in  the  rear  cock- 
pit. Tin-  a< n.  ral  arrangement  of  this  gun  mounting  is 
slio«n  in  (I,,  sketch.  Fig.  18.  The  gun  ring  itself  is  built 
up  »f  thin  three-ply  wood,  and  runs  on  small  rollers  on 
its  support  so  as  to  reduce  friction.  It  is  prevented  from 


tilting  up  by  wooden  angle  pieces  screwed  to  its  undcr- 
siil.-  and  overlapping  the  fixed  support. 

The  machine-gun  is  supported  on  the  gun  ring  l>\  -i 
swivelling  fork,  which  can  be  raised  and  lowered  as  re- 
quired, and  which  can  be  locked  in  any  desired  position 
by  the  locking  arrangement  indicated  in  the  sketch  of 
the  general  arrangement.  In  addition  to  its  circular  mm. 
ment  integrally  with  the  gun  ring,  the  machine-gun  may 
be  swung  laterally  on  its  pivot  in  the  gun  ring.  Her.- 
also  a  locking  device  is  provided  in  the  shape  of  a  split 
collar  locked  by  an  I.  bolt,  as  shown  in  one  of  the  insets. 
The  other  inset  in  Fig.  18  shows  the  lever  by  means  of 
which  the  gun  ring  is  locked  in  any  desired  position. 

As  presumably  it   frequently   happens  that  the  gunner 


«t.  «—C«o«r«l  •mntftmtat  of  the  .pp.r  fcrft-bwxl  wing  at  ln«  AIb«tro.  blpte*.  to 


180 


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wishes  to  fire  from  a  standing  position  his  seat  has  been 
so  arranged  as  to  swing  into  a  vertical  position  as  soon 
as  it  is  relieved  of  its  weight.  This  is  accomplished  by 
means  of  a  spring  under  the  seat,  as  shown  in  Fig.  19, 
which  is,  we  think,  self-explanatory.  A  strip  of  wood 
runs  transversely  under  the  seat  and  projects  a  short  dis- 
tance on  either  side.  These  projections  rest,  when  the 
seat  is  in  a  horizontal  position,  in  brackets  secured  to  the 
sides  of  the  fuselage. 

The  Albatros  biplane  belongs  to  the  C  class,  that  is 
to  say,  is  a  general  utility  machine  variously  used  for 
fighting,  reconnaissance,  artillery  spotting  and  photog- 
raphy, and  is  therefore  not  to  be  considered  a  bombing 
machine.  It  is,  however,  provided  with  racks  for  a  small 
number  of  bombs  —  four,  to  be  exact  - —  presumably  by 
way  of  cases  of  emergency  when  a  suitable  target  might 
present  itself.  Fig.  20  is  a  diagrammatic  perspective  view 
of  the  bomb  racks  and  bomb  release  gear.  The  bombs  are 
secured  underneath  the  main  tank  in  the  pilot's  cockpit, 
but  they  are  released  by  the  gunner  in  the  rear  cockpit  by 
means  of  a  small  lever  and  quadrant  shown  in  Fig.  20. 

The  bomb  racks  are  in  the  form  of  sheet  steel  sup- 
ports, against  the  bottom  of  which  rest  the  nose  and  the 
tail  of  the  bombs  respectively.  These  brackets  are  se- 
cured to  transverse  members  in  the  bottom  of  the  fuselage, 
which  have  been  omitted  in  the  drawing  for  the  sake  of 
clearness.  The  bombs  themselves  are  supported  by  a 
steel  strap  or  band,  passing  underneath  and  approximately 
under  the  middle  of  the  bombs.  At  one  end  the  straps 
are  hinged,  while  at  the  other  they  are  provided  with  an 
eye,  which  is  secured  in  the  hook  under  the  release  trigger. 
One  of  the  sketches  in  Fig.  20  shows  in  more  detail  the 
hook  in  which  the  eye  of  the  strap  rests,  and  the  trigger 
by  means  of  which  the  strap  is  released.  The  trigger  is 
pivoted  near  its  centre,  and  has  an  upward  projection  to 
which  is  attached  a  small  coil  spring  resting  in  a  groove 
in  the  base  supporting  the  hook.  When  the  cam  on  the 
transverse  shaft  presses  down  the  rear  end  of  the  trigger, 
the  front  end  moves  upward  against  the  tension  of  the  coil 
spring  mentioned  above,  thus  releasing  the  strap  and  with 
it  the  bomb. 

As  regards  the  cams  which  operate  the  bombs,  these  are 
mounted  on  a  transverse  shaft  running  across  the  bottom 
of  the  fuselage.  There  are  four  cams,  each  operating  its 
trigger,  but  the  gearing  of  the  camshaft  is  such  that  it 
requires  five  pulls  on  the  lever  in  the  gunner's  cockpit 
to  rotate  the  shaft  through  a  complete  revolution.  One 
of  these  pulls  of  the  lever  has  no  corresponding  cam  on 
the  shaft,  and  has,  it  appears,  been  incorporated  in  order 
to  provide  an  equivalent  of  a  safety  catch.  When  all  the 
bombs  are  in  place  the  first  pull  on  the  lever  does  not 
release  a  bomb,  but  merely  brings  the  cam  for  bomb  No. 
1  into  position,  ready  to  press,  on  the  next  pull  of  the 
lever,  the  trigger  for  the  first  bomb.  This  has  evidently 
been  done  as  a  precaution  against  accidentally  releasing 
a  bomb  until  the  machine  is  approaching  an  objective. 

We  now  come  to  consider  the  method  of  operating  the 
transverse  camshaft.  Near  the  right-hand  side  of  the 
fuselage  there  is  mounted  on  the  camshaft  a  small  ratchet 
having  five  teeth,  as  shown  in  Fig.  20.  On  this  ratchet  is 


a  small  cam,  roughly  of  cone  shape.  This  cam  engages 
with  grooves  in  the  pulley  around  which  passes  the  operat- 
ing cable.  A  small  leaf  spring  engages  at  the  proper  mo- 
ment with  the  notches  in  the  ratchet  and  prevents  the 
shaft  from  rotating  in  the  reverse  direction.  One  end 
of  the  operating  cable  is  attached  to  a  coil  spring  secured 
to  the  side  of  the  fuselage,  and  passes  from  there  around 
the  pulley  to  the  lever  in  the  gunner's  cockpit.  Assuming 
that  the  first  cam  is  in  position  ready  to  release  its  bomb, 
a  backward  pull  of  the  lever  rotates  the  pulley  and  with  it 
the  ratchet  and  camshaft,  thus  pressing  down  the  trigger 
of  one  of  the  bomb  racks  and  releasing  a  bomb.  When 
the  gunner  releases  the  lever  this  is  pulled  forward  to  its 
normal  position  by  the  spring  on  the  side  of  the  fuselage. 
The  little  leaf  spring  engaging  with  the  ratchet  prevents 
this  and  the  shaft  from  following  the  pulley  round  in  the 
opposite  direction,  and  the  cam  on  the  ratchet  sliding  up 
the  sloping  bottom  of  one  of  the  five  grooves  in  the  face 
of  the  pulley  forces  the  pulley  away  from  the  ratchet 
against  the  compression  of  a  small  coil  spring  shown  in 
the  sketch.  By  the  time  the  lever  has  reached  its  for- 
ward position,  the  pulley  has  revolved  to  sucli  an  extent 
as  to  bring  the  cam  on  the  ratchet  into  the  next  groove  in 
the  pulley,  and  when  the  lever  is  again  pulled  the  whole 
action  is  repeated.  The  sketch  will  probably  help  to  make 
the  action  clear. 

In  addition  to  a  bomb  release  lever,  there  is  in  the  gun- 
ner's cockpit  another  lever,  the  function  of  which  appears 
to  have  been  to  engage  and  disengage  a  clutch  near  the 
engine,  by  means  of  which  a  drum  is  operated  carrying 
the  aerial  of  the  wireless.  In  the  bottom  of  the  gunner's 
cockpit,  near  the  left-hand  side,  is  an  octagonal  opening 
in  the  floor,  in  which,  so  far  as  we  can  make  out,  the 
camera  was  mounted.  The  compass,  so  as  to  be  visible 
from  both  cockpits,  has  apparently  been  mounted  in  a 
circular  opening  in  the  right-hand  lower  main  plane. 

We  now  come  to  deal  with  the  wings  of  the  Albatros. 
These  are,  generally  speaking,  of  the  construction  favored 
by  the  Albatros  designer,  that  is  to  say,  the  front  spar  is 
well  forward  close  to  the  leading  edge,  and  the  rear  spar 
is  approximately  half-way  along  the  chord.  In  addition, 
there  is  a  third  false  spar,  which  is  not,  however,  con- 
nected up  to  the  body  nor  supported  by  any  struts,  and 
which  cannot  therefore  be  considered  as  taking  any  par-  . 
ticularly  important  part  of  the  load.  It  'will,  therefore, 
be  realized  that  the  rear  main  spar  may  at  small  angles 
of  incidence,  when  the  centre  of  pressure  moves  back-J 
wards,  be  called  upon  to  support  all  or  nearly  all  of  the 
load.  This  has  evidently  been  guarded  against  in  the 
Albatros  by  making  the  rear  spar  of  generous  proportions. 
Both  main  spars  are  made  of  spruce,  and  are  of  the  box 
type,  consisting  of  two  halves  spindled  out  and  glued 
together  with  a  hardwood  tongue  running  through  both 
flanges.  The  ribs  are  of  I-section,  with  spruce  webs  and 
ash  flanges.  Between  the  main  spars  false  ribs  are  em-] 
ployed  half-way  between  the  adjoining  main  ribs,  so  as] 
to  better  preserve  the  curvature  of  the  wing  for  this  dis- 
tance. 

The  general  arrangement  of  the  upper  left-hand  wing 
is  shown  with  dimensions  in  F'ig.  21,  from  which  the  gen-j 


SI\(;i,K   MOTOKKl)   AKKOl'L. \.\I.S 


Ihi 


i  ral  lay-out  of  tin-  wing  will  he  clear.  Tin-  intrrn;il  drift 
wiring  is  in  the  form  nl  the  Lays,  tin-  i-iiiii|irrssiiiii  struts 
fur  this  wiring  being  in  tin  form  of  circular  section  steel 
tulii-s.  Iii  the  two  nun  r  l>.i\s  both  drill  :uid  anti-drift 
wins  arc  in  duplicate  and  arc  approximately  1  li  S.\\'.(i. 
Tin  nc\t  two  hays  !ia\e  single  wiring.  ,-ilso  of  1  v!  S.\\'.(i., 
while  the  outer  Itay  has  single  wiring  of  I  1-  S.W.G. 

The  attachment  for  the  compression  tulies  and  tin-  drift 
and  anti-drift  wires  is  shown  in  Fig.  22.  A  box  of  thin 
sheet  steel  surrounds  the  spar  at  this  point  and  is  bent 
o\er  and  liolted  as  shown  in  the  small  section  in  Fig.  22. 
On  the  inner  face  of  the  spar  this  sheet  steel  box  has  two 
wiring  plates  stamped  out.  which  receive  the  drift  and  anti- 
dritt  wires.  A  short  cylindrical  distance  piece  is  welded 
on  to  tin  lio\.  and  around  this  tits  a  short  tubular  sleeve 
held  in  position  by  a  slit  pin.  This  sleeve  forms  a  soekct 
for  the  tubular  compression  strut. 

Vertically  the  spar  is  pierced  at  this  point  by  three 
holes,  for  the  holts  securing  the  interplane  strut  and  the 
two  interplane  cables.  The  attachment  for  the  latter  is 
shown  in  Fig.  •_>•,'.  The  base  plate  has  machined  in  it  two 
recessed  circular  openings  which  receive  the  two  terminals 
for  the  cables.  These  terminals  are  prevented  from  ro- 
tating by  a  small  rivet  as  shown  in  the  sectional  view.  In 
order  to  further  strengthen  the  spar  at  the  point  win-n- 
it is  pierced  by  these  three  bolts,  the  spar  ia  left  solid  for 
a  short  distance  on  each  side  of  the  box,  and  packing 
pieces  an-  interposed  between  the  box  and  the  spar,  so  as 
to  bring  it  up  to  an  approximately  rectangular  section  in 
order  to  get  the  bolts  coming  through  the  spar  and  base 
plate  at  right  angles. 

In  1'ig.  •.':>  are  shown  sections,  to  scale,  of  the  two  main 
spars,  the  false  spar,  and  the  leading  edge.  The  trailing 
edge  is.  as  in  the  majority  of  German  machines,  in  the 
form  of  a  wire. 

Fig.  •„' t  shows  the  shape  and  dimensions  of  the  wing 
section.  As  in  nearly  all  German  machines,  the  camber 
is.  it  will  !«•  seen,  extremely  great,  both  as  regards  the 
upper  and  lower  surface. 

The  precise  object  of  employing  such  a  wing  section 
is  not  at  once  apparent,  but  it  should  be  remembered  that 
the  German  machines  carry  a  comparatively  great  load 
per  square  foot  of  wing  surface,  and  the  probabilities  are 
that  the  section  has  been  designed  with  a  view  to  enable 
the  wing  to  support  this  high  load  at  comparatively  great 
altitudes,  and  has,  therefore,  probably  an  excess  resist- 
ance at  lower  levels. 

In  addition  to  the  general  construction  drawings  of  the 
Albatros  wings,  shown  in  a  previous  illustration,  we  are 
able  to  gi\e  some  of  the  more  interesting  constructional  de- 
tails. Fig.  26  shows  some  details  of  the  upper  left-hand 
wing  near  the  tip,  and  also  the  general  arrangement  of  one 
of  the  ailerons.  As  will  be  gathered  from  the  sketch  at  the 
left  top  of  Fig.  •„'<>.  the  wing  flaps  are  built  up  of  steel 


tubing  throughout,  and  each  aileron  is  balanced  by  a  for- 
ward projection,  not.  as  in  the  dothas.  outside  the  tip  of 
the  main  wing,  but  working  in  an  opening  ill  the  main 
plan.-.  As  in  ne.irly  all  German  machines,  the  aileron  is 
not  hinged  to  the  rear  main  spar,  but  to  a  third  false  spar 
situated  between  the  rear  main  spar  and  the  trailing  edge. 
The  method  of  hinging  the  aileron  will  U-  clear  from  the 
detail  section  and  elevation  at  A.  A.  st.cl  clip  is  bent  o\cr 
the  tube  of  the  aileron  and  has  its  forward  ends  bent  into 
grooves  in  wood  blocks  on  the  front  face  of  the  spar, 
much  in  the  same  manner  as  was  employed  in  the  ease  of 
the  elevator  hinge  ami  di-scriln-d  when  dealing  with  that 
member.  As  in  the  case  of  the  elevator  hinge  the  fabric 
covering  of  the  wing  flaps  is  attached  to  wood  blocks 
screwed  to  the  tube. 

The  crank  lever  for  operating  the  wing  flap  is  in  tin- 
form  of  an  elliptical  section  tube  tapering  towards  its  ends. 
I'.ach  half  of  this  crank  lever  carries  three  wiring  clips, 
as  shown  at  li.  It  will  be  seen  that  by  providing  three 
clips  on  each  end  instead  of  one.  a  means  for  varying  tin- 
gearing  of  the  wing  flap  control  is  furnished.  If  a  pilot 
wishes  the  machine  to  be  fairly  sensitive  on  the  lateral 
control  he  will  naturally  attach  his  wing  flap  cables  to  tin- 
inner  clips,  since  thereby  a  movement  of  the  control  lever 
will  result  in  a  larger  movement  of  the  wing  flap.  On 
the  other  hand,  if  be  prefers  to  have  a  large  movement 
on  his  control  lever  without  too  great  corresponding  angu- 
larity of  his  wing  Haps  or  ailerons.  In-  will  attach  his  cables 
to  the  outer  clips,  as  this  will  result  in  a  "  gearing  down  " 
of  the  wing  flap. 

The  forward  end  of  the  wing  flap  crank  lever  works  in 
a  slot  between  two  closely  spaced  ribs,  as  shown  in  the 
sketches.  At  this  point  the  ribs  are  strengthened  by  mak- 
ing them  of  the  box  type  for  their  rear  portion,  and  the 
ash  flanges  of  the  ribs  arc  left  wider  over  this  portion, 
while  being  reduced  to  their  normal  width  from  the  rear 
spar  forwards,  as  indicated  in  the  sketch.  At  this  point 
also  occurs  the  strut  and  lift  cable  attachment.  This 
strut  being  the  last,  there  is  only  one  cable  instead  of  the 
two  occurring  where  the  inner  struts  are  attached,  other- 
wise the  attachment  is  similar  in  principle  to  the  usual 
(ierman  practice.  The  spar  box  and  strut  and  cable  at- 
tachment is  indicated  in  the  detail  sketch  at  C'.  The  tubu- 
lar compression  strut  is  secured  in  the  same  manner  as 
that  of  the  fitting  previously  referred  to. 

As  previously  pointed  out,  the  trailing  edge  of  the  Alba- 
tros wings  in  in  the  form  of  a  wire,  and  the  method  whereby 
the  outer  main  rib  is  prevented  from  bending  sideways  is 
illustrated  in  the  detail  sketches  at  I)  and  I  In  addi- 
tion to  the  wire  forming  the  trailing  edge,  there  in  another 
wire  running  parallel  to  it  and  carried  right  through  the 
wings,  the  object  of  which  appears  to  be  to  provide  a 
counterpoise  capacity.  The  wiring  in  the  Albatros  is  not 
extensive,  and  in  the  case  of  the  fuselage  it  is  absent  alto- 


.  2t_Tt»  wing  Mellon  of  Ibt  AllMlrol  btplu*. 


182 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Fig.  ^5.     The  spar  box  and  its  attachment  to  the  fuselage  of  the  Albatros  fighting  biplane 


gether,  and  it  therefore  appears  probable  that  the  thin 
cables  running  along  the  wings  and  the  longerons  of  the 
fuselage  serve  the  purpose  of  providing  the  necessary 
amount  of  wiring,  otherwise  one  is  at  a  loss  to  account 
for  their  function. 

It  has  always  been  customary  for  German  aeroplane 
designers  to  provide  some  easy  means  for  quickly  detach- 
ing the  wings  from  the  body,  and  the  present  Albatros  is 
no  exception  from  the  rule  in  this  respect.  The  cables 
themselves  are  not,  it  is  true,  fitted  with  the  quick  release 
devices  one  finds  on  the  L.V.G.,  for  instance,  but  the  spar 
attachment  has  been  designed  to  facilitate  the  removal  of 
the  wing,  even  if  that  of  the  cables  has  not.  In  Fig.  25  is 
shown  the  spar  box  and  its  attachment  of  the  lower  wing. 
A  sheet  steel  box  surrounds  the  root  of  the  spar,  and  has 
in  its  end  a  slot  into  which  fits  the  lug  secured  to  the 
side  of  the  body. 

Welded  to  the  side  of  the  spar  box  is  a  socket  forming 


a  bayonet  joint,  into  which  fits  a  pin  fitted  with  a  small 
spiral  spring.  The  spar  is  held  against  the  side  of  the 
body  with  the  lug  projecting  into  the  spar  box,  and  the 
pin  is  inserted  and  given  a  twist  so  as  to  bring  the  pro- 
jections on  the  pin  into  the  notches  in  the  bayonet  joint, 
and  the  spar  is  secured.  For  removing  the  wing  all  that 
has  to  be  done  is  to  press  the  pin  slightly  against  the 
action  of  the  spiral  spring,  give  it  a  twist  and  pull  it  out 
of  its  socket,  and  the  spar  can  be  withdrawn.  The  spar 
is  secured  to  the  spar  box  by  screws,  and  the  box  is  fur- 
ther secured  against  tensional  loads  by  a  steel  strip  about 
a  foot  long  running  along  the  face  of  the  spar  and  an- 
chored at  its  other  end  by  a  bolt  passing  horizontally 
through  the  spar. 

As  the  lower  wing  spars  are  subject,  in  addition  to 
the  bending  moment  owing  to  the  lateral  load  on  them, 
to  tension,  the  attachment  to  the  body  has  to  be  such  that 
it  will  resist  a  tensional  load  as  well. 


Fig.  26.     The  wing  flap  and  some  wing  details  of  the  Albatros  fighting  biplane 


SINCI.K  MOTORED  AKU(  )IM  A  \  I  - 


IH.M 


The  Inn  to  which  the  spar  is  attached  tits  into  a  recess 
in  the  h.ise  plate  formed  by  stamping.  Tin-  i\i-il  pull 
is  transmitted  across  tin  luittiiin  of  the  t'usi  la^c  via  the 
brackets  .-mil  strips  shown,  which  .-ire  bolted  to  the  base 
plat,  holding  the  lug.  In  order  to  prevent  tin-  lug  from 
tiirnini;  it  is  riveted  by  four  rivets  as  indicated. 

The  upper  planes  are  attached,  as  in  nearly  all  (.er 
man  iiiacliiin  s.  to  a  four-legged  cabane.  In  addition  to 
supporting  the  win^s  the  cahane  of  the  Alhatros  carries 
the  radiator,  wliirli  is  of  the  same  shape  as  the  wing 
siction  and  winch  tits  into  an  opening  in  the  wing.  The 
raliane  is  shown  in  Fig.  -J7.  It  will  he  seen  that  one  of 
the  cahaiie  legs  carries  for  a  short  distance  the  water  tube 
from  tin  radiator  to  the  engine. 

The   attachment   of  the   upper  wing  spars  to  the  e  d.  in. 
is   somewhat    similar   to   that   of  tilt-  lower  spars,  inasmuch 
as  a   pin  fitted  with  a  spiral  spring  secures  the  spar  to  the 
raliane.       Here,    however,    tin-    similarity    ceases.       Instead 
of  the  spar  lio\   into  which  tits  the  lug  on  tin-  side  of  the 
body,    the    upper    spars    are    provided    with    n    forked    lug, 
irohalily  a  forging  machined  to  shape,  of  the  form  shown 
n   l'ig.   28.      Tin1  lug  of  the  opposite  spar  is  of  the  same 
Impc.   lint    is.   of  course,   reversed,  so  that   when   the  two 
pars  meet   against   the  top  of  the  cahane.  their   respective 
ar.    staggered   in  relation  to  one  another.      From  the 
mil   attachment   of   the   lugs  it   will   lie   seen   that  as 
hcv    ar.    staggered  on  the  spar  and  in  relation  to  one  an- 
ithir.   the    spars   will,   when   in    plaee.   come   in   line   with 
•lie    another.      On   one   of  the   outer    faces   of   the    forked 
iiiice    is    left    solid,   and    is    shaped    to    receive    the 
onnded  end  of  the  op|«(site  lug.     This  has  prohably  been 
lone  in  order  to  reduce  the  shearing  stress  on  the  pin  se- 
•uriiiir  tin-  lugs  to  the  cabane. 

The    wing-Hap    crank-lever    of    the    lateral    control    is 
lori/ontal.  as   in   so   many  other  German   machines.      The 
untrol  cahlcs   for  the  wing-Haps  are.  therefore,  arranged 
in  vv  hat  unusual  way.      The  details  of  this  arrange- 
ire  shown  clearly  in  Fig.  .SO.      From  the  front  and 
rear  half  of  the  wing-flap  crank-lever  cables   pass  down 
o  pulleys  enclosed  in  a  casing  mounted  on  the  rear  face 
if  the  hack  spar  of  the  lower  plane.     After  passing  over 
'iilleys    the    control    cables    pass    through    the    rear 
*p«r  to  another  pair  of  pulleys  mounted  on   the  tubular 
•onipr.  ssion  strut,  and  hence  to  the  controls  in  the  body. 
\  light  framework  surrounds  the  pulleys  as  shown  in  the 
sketch,  and    forms   the   support   for   the  hinged   inspection 
v   means  of  which  the  condition  of  the  pulleys  and 
rontrol    cables    may    be    examined.     The    tension    of    the 
P  control   cables   in  regulated   by   means   of   turn 
-    inside    the    lower    wing.      These    tiirnbnckles    are 
situated  close  to  the  side  of  the  body,  and  are   rendered 
ihle   by   hinged   aluminium   inspection  doors  on   the 


lower  surface  of  the  bottom  wing.  In  order  to  pnv.nt 
the  tnrnhiicklcs  lr..m  .-at.'hing  against  the  .  .1^.  s  of  the 
wing  rilis.  cables  and  tiirnbnckles  arc  surround.  <l  lit  a 
tube  of  aluminium,  lining  on  its  under  side  an  o|iciiing 
with  edges  Hanged  outwards  to  reduce  the  danger  of  a 
slack  control  cabl«-  allowing  the  turnhuckh  to  touch  the 
edges  of  the  opening  ill  the  tube. 

\-  in  the  majoritv  of  modern  tractor  aeroplanes,  the 
undercarriage  of  the  Albatros  is  of  tl  p.  .  and  i» 

built  of  sin  am  line  steel  tubing  throughout.  Th< 
eral  arrangement  of  tin-  undercarriage  i»  shown  in  I 
--'!».  from  which  it  will  be  seen  thnt  only  the  front  pair 
of  undercarriage  struts  are  diagonally  braced  by  cable*. 
Reference  has  alrcadv  been  made  to  the  claw  brake,  and 
to  the  manner  in  which  it  is  opi  rated  from  the  pilot's 
cockpit.  In  the  sketch  its  general  arrangement  will  In- 
evident.  The  front  and  rear  struts  of  the  undercarriage 
fit  into  split  sockets  at  the  top  and  liottom  rcs|icctivcly. 
from  which  they  may  he  withdrawn  by  undoing  the  bolts 
of  the  socket,  thus  facilitating  replacement  in  case  of  dam- 
age due  to  a  rough  landing. 

Front  and  rear  strut  sockets  are  attached  to  the  body 
in  a  slightly  different  manner,  as  will  be  seen  from  the 
sketches  of  Fig.  29.  In  the  case  of  the  front  strut  sockets 
these  arc  welded  to  a  wide  steel  strip  passing  underneath 
the  bottom  of  the  body,  thus  tending  to  distribute  the  load 
over  a  greater  area  of  the  body.  The  details  arc  .shown 
in  the  general  arrangement  sketch,  and  in  V.  Fig.  'J!». 
.lust  inside  the  strut  socket  the  cup-shaped  terminal  for 
the  diagonal  bracing  cables  of  the  undercarriage  is  sc- 
i  ured.  while  a  short  distance  above  the  socket  in  situated 
the  attachment  for  one  of  the  main  lift  cables.  This  ball 
and  socket  joint,  which  is  used  with  slight  variations  on 
nearly  all  dermaii  machines,  appears  to  be  almost  tin- 
only  tilting  that  may  be  truly  said  to  have  been  standard- 
ized by  the  Germans.  It  is  made  in  a  range  of  sizes,  no 
doubt  all  made  to  some  uniform  standard,  so  as  to  render 
it  applicable  to  a  number  of  different  types  of  machines. 
The  details  of  the  fitting  are  indicated  in  i  and  X,  Fig.  29. 
The  base  plate  securing  the  hemispherical  socket  to  the 
body  or  whichever  part  of  the  aeroplane  the  terminal  hap- 
pens to  be  attached  to.  is  recessed,  probably  by  stamping. 
and  into  this  recess  fits  the  Hange  of  the  socket.  The 
socket  itself  is  free  to  turn  in  the  circular  recess  of  the 
base  plate,  thus  allowing  the  cable  to  accommodate  itself 
to  any  angle  desired.  The  end  of  the  turnbuckle  has  two 
Hats  on  its  shank  which  prevent  the  strainer  from  turn- 
ing. For  purposes  of  adjustment  the  slot  in  the  socket 
is  enlarged  at  its  inner  end  so  as  to  allow  the  strainer 
to  turn  when  in  a  position  at  right-angles  to  the  base  plate. 

The  attachment  of  the  rear  chassis  strut  to  the  Ixidy  is 
shown  in  :>,  Fig.  29.  The  base  plate  to  which  the  strut 


I'hr  c.b.ne  supporting  the  radiator  ami  upper  plane    Fig-  *•     -Sketch  showing  lup  on  mot  »f  upper  main  wing  .par. 
•>f  the   \llmtros  biplane.     Note  the  manner  of  carrying  the  water 
•hrouph  one  of  the  culiane  legs 


184 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


socket  is  welded  is  of  angle  section,  and  is  secured,  via 
brackets  as  shown,  to  steel  strips  running  across  the  body, 
and  which  take  the  tension  of  the  lift  cables.  This  ar- 
rangement is  somewhat  similar  to  that  of  the  lower  wing 
spar  attachment,  which  we  described  in  a  recent  issue. 

The  lower  ends  of  the  two  Vees  are  formed  by  short 
lengths  of  bent  tube  of  slightly  larger  dimensions  than 
the  struts  themselves,  for  which  they  form  sockets.  The 
details  will  be  evident  from  the  sketches  and  hardly  need 


any  explanation.  Running  across  the  undercarriage  par- 
allel with  the  axle  are:  in  front  a  compression  tube,  and 
behind  a  stranded  cable. 

A  steel  strip  protects  the  rubber  shock  absorbers  from 
contact  with  the  ground,  and  a  padding  of  leather  is  in- 
terposed between  the  axle  and  the  bottom  of  the  Vee. 
The  upward  travel  of  the  wheel  axle  is  limited  by  a  short 
loop  of  cable,  against  which  the  axle  comes  to  rest  after 
travelling  the  permissible  amount. 


Side  view  of  the  Albatros  C-V  Fighter 


The  chassis  of  the  Albatros  C-V  Tvp« 


SIN<;I.K   MOTOKK1)   AKK01M..\M> 


185 


THE    FOKKER    SINGLE-SEATER 
BIPLANE.    Type    D.7. 


SPAN        

CIKIkll  TOP  PLANE 

.,     BOTTOM     .. 
OVERALL  LENGTH 
TAIL  PLANE  SPAN 
MEKiMT  ... 
AIRSCREW 

GAP  

STAQQER 
ENOINE 


4-  r  ,. 
i  iir.. 

Mercedes  160  h  p. 


186 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Three  views  of  the  Fokker  Single  Seater 

The  Fokker  Single  Seater  Biplane — Type  D-7 


This  aeroplane  presents  features  of  very  great  inter- 
est, whether  viewed  from  the  standpoint  of  aerodynamic 
design  or  of  actual  construction.  The  machine  which  has 
been  the  subject  of  investigation  was,  unfortunately, 
rather  extensively  damaged,  thus  making  absolute  ac- 
curacy of  description  difficult,  and  trials  of  performance 
impossible. 

A  similar  machine,  however,  has  been  tested  for  per- 
formance by  the  French  authorities,  who  have  issued  the 
following  report: 


1,000 
2,000 
3,000 
4,000 
5,000 


Altitude 

metres 

(3,281   ft.) 

(6,563  ft.) 

(9,843  ft.) 

(13,124  ft.) 

(16,405  ft.) 


Time  of  climb 
4  mins.  15  sees. 
8  mins.  18  sees. 
3  mins.  49  sees. 

;2  mins.  48  sees. 

38  mins.     5  sees. 


The  principal  dimenjfens  are  as  follows: 

Span     

Chord   (upper  wing  ) 

Chord    (lower  wing)    

Overall   length    

Gap    

Area  of  upper  wings   (with  ailerons)    


Speed  at 
this  height 

116.6  m.p.h. 
114.1  m.p.h. 

109.7  m.p.h. 
103.5  m.p.h. 

94.9  m.p.h. 

29  ft.  3 1/2  ins. 

5  ft.  2  y2  ins. 

3  ft.  Ily4  ins. 
22  ft.  ll>/2  ins. 

4  ft.     2      ins. 
. . .   140.7  sq.  ft. 


Area  of  lower  wings   78.3  sq.  ft. 

Area  of  aileron   (one  only)    5.7  sq.  ft. 

Area  of  balance  of  Aileron   5  sq.  ft. 

Area  of  horizontal  tail  plane   21.1  sq.  ft. 

Area  of  elevators    15.2  sq.  ft. 

Area  of  balance  of  elevator  l.l  sq.  ft. 

Area  of  fin    2.8  sq.  ft. 

Area   of   rudder .5.9  sq.  ft. 

Horizontal  area  of  body   35.6  sq.  ft. 

Vertical  area  of  body   58.6  sq.  ft. 

Area  of  plane  between  wheels   12.4  sq.  ft. 

The  following  data  regarding  weights  is  taken  from  a 
French   source : 

Weight  of  fuselage,  complete  with  engine,  etc 1. 3 •-'•.'. 2  Ibs. 

Weight  of  upper  wing  with  ailerons   167.2  Ibs. 

Weight  of  lower  wing   99.0  His. 

Weight  of  fin  and  rudder   6.6  Ibs. 

Weight  of  fixed  tail  plane   17.6  Ibs. 

Weight  of  elevators    9.9  Ibs. 


1,622.5  Ibs. 
Wings 

As  in  the  Fokker  triplane,  the  extreme  depth  of  wing 
section  and  the  absence  of  external  bracing  are  distinctive 
features.  Both  upper  and  lower  wings  are  without  di- 
hedral, and  are  in  one  piece. 


SINCiLK   MOTOKKI)  A  KHOI'I  .A  M -s 


Sections    of    111!'    willL'    -p.-ir    of    tl»-     l-'l 

1)7 


»»*    3. 


:.   4. 


Wing  Construction 

In  sharp  contradistinction  to  the  fuselage,  which  is  con- 
st ructcd  of  stcrl  even  inclndim;  members  where  wood 
is  almost  tmi\i  rs.-illy  used,  the  wings  contain  no  metnl 
parts,  if  we  exclude  strut  fittings  and  other  extraneous 
features.  There  are  no  steel  compression  members,  hut 
where  the  internal  wiring  lugs  occur,  special  box-form 
compression  ribs  are  fixed.  The  leading  edge  is  of  very 
thin  three-ply,  which  has  a  deeply  serrated  edge,  finish- 
ing on  the  main  spar.  The  ribs  are  of  three-ply,  and  are 
not  lightened,  although  holes  are,  of  course,  cut  where 
irv,  to  accommodate  the  control  and  bracing  wires. 
A  rib  from  the  top  center  section,  and  one  from  the  root 
of  the  lower  wing,  are  both  drawn  to  scale.  See  Fig.  1. 

The  extreme  thinness  of  the  three-ply  has  given  rise 
to  a  new  method  of  fixing  the  flanges,  on  the  ribs.  In 
stead  of  grooved  flanges  tacked  on  so  that  the  tacks  run 
down  the  length  of  the  three-ply,  two  half  flanges  of 
approximately  square  section  are  tacked  together  hori- 
•ontally  with  the  ply  sandwiched  between. 


Spars 

As  may  be  seen  from  the  various  sections  drawn  to 
scale  in  Figs.  3  and  4,  the  spars  are  made  up  of  fairly 
narrow  flanges  at  top  and  bottom,  joined  on  either  side 
by  thin  three-ply  webs.  They  arc  placed  approximately 
.So  ems.  apart.  The  flanges  are  made  of  Scots  pine,  and 
consist  of  two  laminations.  The  three-ply  has  the  two 
outer  layers  of  birch  and  an  inner  ply  which  is  probably 
birch  also. 

The  three-ply  webs  are  tacked  on  to  the  flanges,  and 
fabric  is  glued  over  the  joint.  The  cement  is  an  ordi- 
_'<-latine  glue. 

The  spar  webs  are  glued  to  the  flanges  by  a' waterproof 
casein  cement,  which  is  proved  to  contain  gelatine,  while 
the  plywood  adhesive  —  also  a  casein  cement  —  is  water- 


proofed and  of  sufficiently  good  quality  to  withstand  four 
hours'  immersion  in  boiling  water. 

The  trailing  edge  is  of  wire,  and  tape  crosses  from  tin- 
top  of  one  rib  to  the  bottom  of  the  next  in  the  usual  way. 
This  tape  lattice  occurs  about  half-war  between  the  trail- 
ing edge  and  the  rear  spar. 

Fig.  3  shows  the  sections  of  the  front  and  rear  upper 
plane  spars,  taken  in  the  centre  section  and  at  the  inter- 
plane  struts,  while  Fig.  4  gives  the  corresponding  lower 
spar  sections. 

The  ribs  are  stiffened  between  the  spars  by  vertical 
pieces  of  wood  of  triangular  .section.  There  arc  two  such 
pieces  on  each  rib  in  the  upper  plane,  and  one  in  the  lower 
plane. 

All  the  woodwork  of  the  wings  is  varnished,  and  fabric 
is  bound  round  the  flanges  of  the  ribs  and  glued  to  the 
top  and  bottom  of  the  spars. 

The  workmanship  is  decidedly  good,  and  the  finish  neat 
and  careful. 

Struts 

The  struts  are  all  of  steel  tubing  of  streamline  section, 
and  the  centre  section  system  is  particularly  worthy  of 
attention.  All  those  three  struts  which  meet  at  a  point 
on  the  front  spar  of  the  upper  wing  are  welded  to  the 
fuselage  framework,  and  arc  thus  not  removable  when 
the  machine  is  dismantled  (see  Fig.  5).  The  strut  which 
joins  the  rear  upper  spar  to  the  front  lower  spar,  how- 
ever, is  not  welded  but  is  fastened  by  a  ball  and  socket 
joint,  which  is  the  subject  of  Fig.  6.  It  will  be  noticed 
that  the  ball  forms  the  extremity  of  n  threaded  bolt  which 
is  screwed  into  the  end  of  the  strut,  thus  making  it  ]>«- 
sible  to  adjust  the  length  of  the  latter.  Both  ball  and 
socket  are  drilled  and  a  bolt  locked  through  the  hole. 
The  attachment  of  up|>er  centre  section  struts  to  the  wing 
spar  is  shown  in  Fig.  1. 

As  is  made  clear  in  the  scale  drawings,  the  interplane 
struts  are  of  X  shape  when  seen  from  the  starboard  wing 


188 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Fig.  5- 


Fig.  e. 


Hi. ». 


fig.  «7. 


Fig.  8, 


Fig.   10. 


Fig.   12 


KEY    SWITCH 


PRESSURE  CAUSES  •GREASE  PUMP 


ACHTUNG; 

Hohengas* 


FROM   AUXILIARY© 

TANK  jV 


^^  CAUTION 

,HI6H  ALT. THROTTLE  CONTROL 


AIR 

RELEASE  COCK 

PUMP  OFF 

PUMP 
.MOTOR    PUMP 


TO'flUXILHRYY? 
TAM  K 


Fig.  17 


Pig.   IS. 


Fig.  16 


SINCJ.K   MOTOKK1)   A  KKUIM.A  \  I  .s 


IH'.t 


tip.        Till-    tlircr    mrlnllcrs    of    tin      \     are     w  el, led    together, 
and    all    four    In-c    extremities    li;i\r    tlir    :uljiist:ili|i-    attach 
inciit     descrilN  il    abmr.       It     lias    alrrailx      IIIVM     in. -iitinrii  (I 

that    tlnTf    IN    \tern.al    hracing.    tin     win^   , ^instruction 

-ill^'  in  id.-  surticicntlx  strong  against  hit  stresses  |,, 
ohxiite  its  necessity,  anil  tin  form  of  tin-  mtcrplnnc  struts 
is  intcrestin:,'  in  this  i-nnni-i-tiiiii. 

Fuselage 

This  is  exactly  similar  in  design  ami  construction  In  tin- 
triplanc  1  o<lv  allowing.  •>{  course,  fur  tin-  difference 
in  type  of  engine  ami  for  tin-  fart  tli.it  Ixith  wings  h.axe 
twn  spars  instead  of  one.  Tin  longerons  and  cross  struts 
arc  .it  circular  si-rtioii  sli-rl  tube  wrlilril  in  plarr.  and 
carrying  it  the  corner  tin  small  c|iiadrant  of  strrl  tube 
wliirli  cnrrirs  tin-  bracing.  Tin-  diameters  of  these  tubes 
vary  I  rom  M  Minis,  to  IS  nuns.,  and  tin-  strrl  was  of  -2  \ 
gauge  in  tin-  plans  where  tin-  tnlirs  had  lirrn  pirrrrd  by 

bullets. 

This  hr.-irini;  wi  II  repays  attention.  All  sides  of  ,-ach 
section  an-  cross  liracrd  with  piano  win-,  which  is  simplx 
passed  round  tin  two  lugs  to  l«-  joined  ami  has  its  rv 
trnnities  connected  In  means  of  a  tnriiluicklr.  This 
nirthod  has  tlir  great  advantage  that  only  two  loops  are 
nired  in  tin-  wire  instead  of  four,  and  in  consequence 
this  bracing  can  lie  very  rapidly  assembled.  It  is  also 
possiHy  lighter  in  relation  to  its  strength  than  the  usual 
amusement  of  single  wire  bracing.  Fig.  8  shows  how  a 
handle  is  clipped  on  to  the  lower  longerons. 

The  front  part  of  the  body  is  a  particularly  good  piece 
of  welding,  and  includes  the  engine  and  radiator  sup- 
ports a>  well  as  the  arrangement  by  which  the  continuous 
spar-,  of  the  lower  planes  can  be  placed  in  position.  This 
is  dom  by  removing  two  fork-ended  tubes  (one  each  side 
if  the  body),  and  replacing  these  when  the  wings  are  in 
position.  I  i:,'.  <>  shows  how  the  wing  spar  is  joined  to 
the  fuselage  and  Fig.  K)  shows  the  fuselage  joint  at  this 
point. 

Tin-  cowling  is  of  aluminum,  and  covers  the  front  por- 
tion of  the  fuselage  on  all  four  sides.  It  is  extended  on 
the  top  to  the  cockpit,  and  underneath  to  beyond  tin- 
rear  spar.  The  cowls  are  arranged  in  convenient  sheets, 
and  an  t  istem-d  by  means  of  bolts  and  nuts  of  unusual 
The  nuts  ha\e  small  handles  about  1  in.  long, 
which  enable  on.-  to  manipulate  them  without  tools.  From 
. r  half  of  the  cockpit  to  the  junction  of  the  tail  and 
Ixtdy.  the  top  is  furnished  with  a  three-ply  fairing,  which 
•xtends  oxer  not  quite  the  whole  width  of  the  fuselage. 
This  is  shown  in  Fig.  1  1. 

Tail 

I  In    tixeci  tail  planes  and  elevators  are  almost  similar 
to  those  of  the  triplane.  i.e.,  the  tail  is  triangular  and  the 
rs  balaiierd  and  divided,  although  they  are  actually 
n    one    piece.      The    biplane,    however,    has    a    tri- 
angular Hn  whose   foremost  point  is  fixed  an  inch  or  two 
to  tin    port    sale  of  the  centre   line  of  the  machine,  thus 
proxiding  a  surface  which  is  inclined  slightly  to  the  longi- 
•udin-il  axis  of  the  aeroplane.      This  is  illustrated  in   Fig. 
s   is  no  doubt  arranged  to  balance  the  tendency  of 
'•>••  machine  to  turn  to  the  left  in  flight,  due  to  the  slip- 
in. 

I  In    framework   of   the   tail   is   of  circular   section   steel 
throughout,   including  the   trailing  edges,  and  this 


frnnn  work  is  arranged  to  give  the  ti\ed  tail  •  symmetrical 
i  tmbcr.  The  attachment  of  the  tail  plane  to  tin  fuselage 
U  simple  and  etl'r.  In  \  -,  m  t|lr  trip! 

the  top  longeron-,  arc  dropped  at  this  p.. ml  sutlicnntly  to 
allow  the  tail  plain  to  haxe  its  top  surface  Nxi  I  with 
the  top  of  the  fuselage,  and  lime  bolts  passing  through 
the  main  steel  tube  of  the  tail  ami  through  short  piece* 

ot     tube    welded    to    the    |MI<|\      framework    secure    It     il,    this 

' f   the  three   l>olts,  one    is   plan  . I     il    nlliir   side 

of  the  top  of  the  fuselage  on  the  front  of  the  tail,  ami  one 
at  tin    end  of  tin    body    framework.      Tin    tail   pi  nn    i 
at    a    slight    angle    of    incidence        about    ML.    dcgr.  ,  s 
which    is    not    intended    to   IK-   adjustable,   but    which    could 
easily    lie    altered    by    nn  alls   of   a    few    washers    ami    longer 
(Milts.      The   tail   is   stay,  (I    by    two  streamline   section   steel 
struts,  which  connect   tin    rear  lulu-  of  tin    tail   plane  with 
the    lottom   of  the   sternpost.   as   is    shown   by    the   general 
arrangement   drawings.      These   struts  an    not   harlteil. 
1'rom   the   sketch  of  the  tail   skid    (Fig.    1M),  it  will  be 
•i   that   this  member  is   balanced  at   a   point   al>oiit   one 
third  of  its  length  from  its  lower  end.  and  that  the  slnx-k 
absorbing  arrangement  consists  of  two  helical  stec  I  springs. 

Undercarriage 

This  is  a  feature  of  the  machine  which  carries  a  distinct 
trace  of  British  influence.  The  angle  between  the  two 
limbs  of  the  Vee  is  usually,  in  German  aeroplanes,  very 
obtuse;  i.e.,  the  two  top  points  of  attachment  are  widely- 
separated,  while  British  practice  leans  towards  making 
this  angle  fairly  acute.  In  the  Fokker  the  angle  be- 
tween the  struts  is  about  53  degrees.  The  section  of  the 
steel  struts  is  streamlike  in  form,  with  major  and  minor 
axes  of  65  mms.  and  3-1  mms.  respectively.  The  metal  is 
SO  gauge. 

The  upper  attachments  of  the  undercarriage  struts  are 
of  the  ball  and  socket  type,  with  a  bolt  through,  similar 
to  the  interplane  strut  illustrated  above.  The  junction 
of  the  lower  extremities  and  the  slot  which  allows  for 
axle  travel  is  clearly  explained  by  Fig.  I  ^.  The  bracing 
cables,  which  connect  the  upper  extremities  of  the  front 
struts  with  the  opposite  lower  ends,  are  attached  in  the 
usual  manner  to  lugs  welded  on  to  the  struts.  It  in  inter- 
esting to  note  that  in  the  crash  which  wrecked  the  ma- 
chine, one  of  these  lugs  has  torn  out  a  small  piece  of  tin 
sheet  steel  of  which  the  strut  is  formed,  though  there 
is  no  sign  of  fracture  at  the  weld. 

The  least  usual  characteristic  of  the  landing  carriage, 
however,  is  the  provision  of  a  small  cambered  plane  sur- 
rounding the  axle,  just  as  is  the  case  in  the  Fokker  tri- 
plane. This  auxiliary  plane  has  been  badly  battered, 
and  few  details  are  available,  but  the  sheet  aluminium  box 
which  surrounds  the  axle  remains.  This  box  is  rectangu- 
lar in  section,  and  the  edges  arc  riveted  together  on  the 
upper  side.  It  forms  the  main  and  only  spar  of  the  plane. 
the  construction  of  which  is  \er\  similar  to  that  of  the 
main  plane.  Tin-  shock  ahsorlx-rs  are  of  the  coil  spring 
type,  and  are  wrapped  in  the  manner  illustrated  in  Fig. 
lY  The  wheels  are  760  X  100. 

Engine  and  Mounting 

The  engine  is  a  Mercedes  of  1HO  h.p.  A  full  report  on 
this  type  of  engine  has  already  been  issued,  but  the  pres- 
ent example  possesses  one  or  two  minor  points  of  differ- 
ence from  the  standard.  The  chief  of  these  is  the  fact 


190 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


that  this   engine   has   domed   pistons,   giving  higher   com- 
pression. 

As  has  already  been  mentioned,  the  engine  bearers  are 
steel  tubes,  supported  on  a  steel  tubular  structure  welded 
up  integrally  with  the  fuselage  frame  and  with  the  centre 
section  struts.  The  diameter  of  these  two  parallel  tubes 
is  34  mms.  and  the  gauge  14.  Each  tube  carries  four 
"  pads  "  of  the  type  shown  in  Fig.  15,  to  which  the  crank- 
case  is  bolted. 

Radiator 

The  radiator,  as  may  be  gathered  from  the  scale  draw- 
ings and  sketches,  is  of  the  car  type  (another  departure 
from  modern  German  design),  and  is  supported  by  steel 
tubes  which  are  part  of  a  fuselage  frame.  The  radiating 
surface  is  surmounted  by  a  curved  fairing,  of  which  the 
port-side  half  is  a  brass  water  tank,  into  which  the  filler 
leads,  while  the  starboard  side  is  merely  an  aluminum 
fairing.  The  radiator  is  constructed  of  brass  tubes  ar- 
ranged parallel  to  the  engine  crankshaft.  The  tubes  are 
circular  in  section,  but  expanded  into  hexagons  at  either 
end  and  sweated  up  there.  Each  hexagon  measures  7 
mms.  across  the  flats. 

The  single  shutter,  as  will  be  seen  on  reference  to  Fig. 
16,  is  normally  held  open  by  a  spring,  but  can  be  closed 
at  will  by  pulling  a  small  cable.  This  shutter  even  when 
completely  closed  only  puts  out  of  action  a  small  por- 
tion (roughly  about  one-third)  of  the  cooling  surface. 

Petrol  and  Oil  Systems 

There  is  only  one  fuel  and  oil  tank  in  the  machine. 
It  is  of  sheet  brass  and  is  slung  from  cross  tubes  clipped 
on  to  the  top  longerons,  just  in  front  of  the  ammunition 
magazines,  which  are  placed  immediately  in  front  of  the 
pilot. 

So  far  as  can  be  ascertained  from  such  external  evi- 
dence as  is  afforded  by  fillers,  piping,  the  lines  of  rivets 
on  the  tank,  and  the  gauges  and  petrol  cocks,  it  may  be 
said  that  this  tank  is  divided  into  two  petrol  tanks  and 
one  oil  tank.  The  main  petrol  tank  has  a  capacity  for 
61  litres  .(approximately  1  sy2  .gallons),  and  is  provided 
with  a  baffle  plate.  The  reserve  tank  holds  33  litres  (ap- 
proximately 7*4  gallons),  while  the  oil  tank  carries'  4% 
gallons.  From  the  brass  disc  which  is  sweated  to  each 
flank  of  the  tank,  it  would  appear  that  a  tie  rod  passes 
across  the  tank  from  side  to  side.  Both  petrol  tanks  work 
under  pressure,  obtained  initially  by  hand-pump,  and  main- 
tained by  the  usual  mechanical  air-pump.  The  dashboard 
carries,  besides  the  main  switches  and  a  starting  magneto, 
a  two-way  cock  which  allows  the  pilot  to  use  petrol  from 
the  main  or  auxiliary  tank,  or  to  shut  it  off  completely. 
A  separate  pressure  gauge  for  each  tank  and  two  two- 
way  air  pressure  cocks  are  also  mounted. 

Throttle  Control 

A  sketch  of  the  throttle  lever,  situated  on  the  pilot's 
left,  is  given  (Fig.  18).  This  lever  actuates  the  car- 
buretor throttle  by  the  means  shown.  The  compression 
tube  between  the  quadrant  and  the  balanced  lever  is  over 
•  four  feet  long  and  about  five-eighths  inch  in  diameter. 
Although  heavy-looking,  this  control  is,  of  course,  made 


of  very  light  gauge  material.  The  adjustment  provided 
at  the  pilot's  end  of  the  control  should  be  noticed.  The 
control  works  in  conjunction  with  a  Bowden  type  lever 
on  the  control  lever,  as  shown  by  Fig.  19.  The  twin 
cables  from  this  auxiliary  throttle  lever  are  attached  to 
the  main  throttle  control  —  Fig.  18  shows  the  attach- 
ments. 

Controls 

The  control  lever  of  the  machine  works  on  precisely  the 
same  system  as  that  of  the  triplane,  but  the  grip  at  the 
head  of  the  column  is  quite  different.  Reference  to  Fig. 
19  will  show  that  the  usual  two-handed  grip  is  replaced 
by  a  single  handle  for  the  right  hand. 

"  The  left  hand  is  free  to  manipulate  the  auxiliary  throt- 
tle control,  inter-connected  with  the  main  throttle  lever. 
It  should  also  be  noticed  that  the  usual  pushes  for  firing 
guns  are  absent,  and  the  interrupter  gear  is  actuated  by 
pulling  either  or  both  of  the  levers  by  the  fingers,  while 
the  thumb  rests  on  the  specially  arranged  place.  There 
is  no  separate  arrangement  for  firing  both  guns  together, 
and  it  is  not  possible  to  lock  the  elevator  controls  in  any 
given  position. 

The  longitudinal  rocking  shaft  carries  at  its  front  end 
two  arms  to  which  the  aileron  control  cables  are  fixed  (see 
Fig.  20).  These  wires  cross;  and  pass  upwards  and  out- 
wards to  aluminium  pulleys  on  ball  bearings,  which  are 
attached  in  pairs  to  a  hinged  sheet  steel  framework.  Or 
the  way  these  cables  pass  through  short  tubular  guides 
fixed  to  the  top  longerons.  The  aileron  levers  follow  con- 
temporary British  practice,  and  project  vertically  above 
and  below  the  plane. 

The  elevator  control  wires  are  taken  direct  from  the 
control  lever,  one  pair  above  and  one  below  the  fulcrum 

The  rudder  bar  (see  Fig.  21)  is  of  neat  and  light  weldec 
construction.  There  is  no  adjustment  to  allow  for  varia- 
tion in  leg-length  of  different  pilots,  but  it  should  be  no- 
ticed that  the  pilot's  seat  is  adjustable  as  regards  height 
The  means  by  which  this  movement  is  obtained  is  exactb 


Fig.   19. 


Control  details  of  the  Fokker  D-7 


SINtil.K    MOTOKK1)  AKUOl'l    \\|> 


1JH 


In    same  as  the  arrangement  in  tin-  triplanc.  i.e.,  the  seat 
•>  a   sheet    aluminium   liuckt  I    uilh    .1   three  ply    bottom   sup 
lorted    by    a    framework    ol    st.,1    tubes    which    grips    the 
_re   cross    struts    In     fnur   clips,   which   c.-in    In-    placed 
it  any  height.      '1'his  i-.  in.-iilc  clear  by   1  'i^. 

Fabric  and  Dope 

The  f.-ihrie  is  nut  attached  in  any  w:iy  In  the  longerons, 
nit  is  simply  carried  oxer  tin-  fuselage  and  laced  ahnii: 
he  bottom  centr.-il  line.  There  is  .1  cross-piece  of  fabric 
aced  to  the  cross  tubes  immediately  behind  the  cockpit. 

The  fabric  is  coarse  flax,  coarser  and  less  highly  eal- 
•ndered  than  the  type  usually  met  with,  and  a  good  deal 
leavier. 

It  is  colour  printed  in  the  usual  irregular  polygons. 
The  bright  red  paint,  mentioned  below,  is  removable  by 
ilcohol,  but  not  soluble  in  it,  coming  off  ns  a  skin  under 
reatment. 

I'nder  the  paint  is  a  dope  layer  —  an  acetyl  cellulose. 
Siit In  r  paint  nor  dope  presents  unusual  features. 

Wrights 

I'. lint       !).'.()  (fins.  |MT  s<|.  m. 

Dopr      (iM.l    (fins.    JUT   s(|.   in. 

I  al.ric      I  i:Ui  (rins.  |«-r  scj.  m. 


mr.{.7  |rms.  per  sq.  m. 

SI  ri-n jtth     1779  k   in. 

Kxtriisinii    7.0  jx-r  cent. 

\Vhere  the  wiiiys  are  not  painted,  the  fabric  is  covered 
vith  a  linn  layer  of  dope  only. 


Schedule  of  Principal  Weights 

Ib*.  oc. 

I  |'|MT  wiii(f,  fiiinpletr  with  .nl.  r,, u-.  jiiillrys  brwinp 

«irr>.  falirir  and  strut  litlinjfs  ! \M  0 

1  OMIT  win);  (mi  ailerons  titled),  complete  uilh  strut 

littiii|r<  and  falin-  -  97  0 

N       I  rut    IH-IUIVII    winj-s  |  •> 

Str.ii^'lit  strut.  U-twiiii  fiis,-|.iL.r  and  trHilliifr  spur  of 

upper  winy  *  8 

\ilenill  Ir.iin.-,  with  hilife  flijls,  witlioilt  f.iliri.  4  8 

It  udder  frame,  with  \\ii\fr  clips,  witlxinl  fnlirir  4  II 

I  in  fr; •.  M  ith<iiit  fnl>ric  1  14 

Tail  planes  (eninplet.  111  .me  plrcr),  without  fabric...  li  6 

I  kvntors  (complete  In  one  piece),  without  fnhrlc  II  9 

It.iiii  itur  einptx  l>»  0 

I  'ndrrcarriafre  strut,  each  2  10 

riulrrcarrUfre  «\lr,  with  shock  itltsorlirr  lioblilnk  1H  8 

Uol.liin.  each  "  : 

Sh<K-k  ahsorlK-r.  each  :«  • 

t'lidrrcarrlaire  (complete ),  without  wheel*  *n<l  tlre», 

and  without  plane,  hut  including  struts  *>  4 

Aluminum  tuhe.  forming  rear  spar  of  undercarriage 

plane  1  8 

Wheel,  without  tire  and  tube  II  8 

Tire  and  tube  9  4 

Tail  strut  I  13 

Fabric,  per  square  foot,  with  diijw 0  1 

Bottom  plane  compression  rib  0  15 

Itottom  plane  ordinary  rib  U  II 

Top  plane  ordinary  rib.  at  centre  of  plane  1  0 

Bracket,  with  holts,  attaching  top  plane  to  fuselage 

struts  1  II 

Main  spar,  top  plane,  including  fillet  for  ribs,  per  foot 

run   in   centre    1  11 

Owing  to  tapering  ends  the  average  weight  per  foot  of 
the  spars  will  be  slightly  less  than  this  figure. 


The  Tarrant  "  Tabor  "  Triplane 


Tarrant   "Tabor."   equipped    with   six    \apier   "I. ion"   rnvines   of  .VN»  h.p.  each.     Spnn   of   tin-    middle  plane   is    1:11    ft.    :»   in. 
Overall  height  is  :»7  ft.  :»  in.     Overall  length.  7:1  ft.  .'  in.     Total  weight.  45,000  pounds 


192 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Gunners  Sea 


Pilots  Seat. 


HALBERSTADT 
GENERAL  DETAILS 
Two-Sealer  Biplane 

Span 35'  3}' 

Gap      4'0'to3'8J' 

Chord  Top  Plane     5'  3i' 

Chord  Bottom  Plane 

Overall  Length         

Tail  Plane  Span       

Height  

Engine  

Set  Back  of  Planes 

Propeller        9'  o' 

Track 6'  4' 

Stagger 2'  o' 


4"  3J- 
.     24'  0* 
.     8'  11* 
9'  6' 
.  160  h.p. 
4° 


PLAN  DRAWINGS  OF  THE  HALBERSTADT  FIGHTER 


The   Halberstadt   Fighter 


This  German  machine  is  a  two-seater  fighter. 

General  Details 

Bristol  Technical  Department  has  stated  that  the  Hal- 
berstadt represents,  in  all  probability,  the  high-water 
mark  of  two-seater  Germa.i  aeroplane  construction,  as  it 
is  not  only  well  and  strongly  constructed,  but  its  general 
behaviour  in  the  air  is  good  according  to  modern  fighting 
standards. 

Span  of  upper  plane  35  ft.  3</i  in. 

Span  of  lower  plane   34  ft.  11  in. 

Chord  of  upper  plane   5  ft.  3'/4  in. 

Chord  of  lower  plane   4  ft.  3'/.,  in. 

Gap,   maximum    4  ft. 

Gap,  minimum   3  ft.  8y2  in. 


Dihedral  angle  of  lower  plane 2° 

Horizontal  dihedral  of  main  planes 4° 

Total  area  of  main  planes   310  sq.  ft. 

Area  of  each  aileron   1  l.S  sq.   ft. 

Area  of  aileron  balance   2.0  sq.  ft. 

Load  per  square  foot    8.2  Ibs. 

Area  of  tail  planes   13.6  sq.  ft. 

Area  of  elevator   12.4  sq.  ft. 

Area  of  fin   6.4  sq.  ft. 

Area  of  rudder   7.9  sq.  ft. 

Area  of  rudder  balance 1.0  sq.  ft. 

Maximum  cross  section  of  body   8.8  sq.  ft. 

Horizontal  area  of  body   44.0   sq.   ft. 

Vertical  area  of  body   52.8  sq.  ft. 

Length  over  all   24  ft. 

Kngine    180  h.p.  Mercedes 

Weight  per  h.p.  (180)    14.0T  Ibs. 


SI\(,I.K   MOTOKK1)   .\KHOIM..\\1  - 


I'.t.'i 


Schedule  of  Principal  Weights 


Tolnl 


! 


Capacity  of  |)rtrul  tank-  :|    .  ,11,, us 

C.lp.inU     "I    oil    Link-  I    i;'lll"!l- 

Crew  I'wn 

(inn-  I    t>\iil  .mil   1  inovHlilr 

Militant    hud   en   t.-xt         .  I.   His.  l  l'l"'r   wi"(f.  «-iiinp|rlr    uith   .ol.r .iili-r.iti    r(Ml.  ilmg 

io.ul  on  tot                                                 '..,.'  II.-  ''-'•    •""'    '>lrut    attachments,    hut    without    lid 

liruriiiir  wirrs   ,n,l  tabfi  .     «/      « 

Performance  I  "«-T  »iiic.  .1*  .il>m.-  <  no  aileron  nttrd)   .                        a      - 

\ilrnm   ( •<nn|ilrtr.  without   fnlirir    . 

S      -'(I  .'it    IO.OIMI  ft..  !»7   ni.p.h..   l.is:>   r.p.m.  \ili-rnn   Imr,  wilh  flnnp- 

It,.,  otrii.nl,     Indicated  |"|"I'|«H-  *«ru«.  '-„,..  .,i|H,,,t 

Mi.,.  inf..    nun.       Airspeed         .'"7 '"  ;tr"  '"*'"'   '"'«;  :«'« 

Cli.,.1,   to  .'..I" N.   ft.                                                     llu                     N  "'I'1''''-'    ttlth    '•••""I'T   «,Ml    itr.vlty 

rii.,,1.   I ,000ft                                                    MO                     -,l  .<•-...( r.,1  ,. rank    .n,M-r»clnK  wirrx           .101       0 

CUmb  to   14000  fl                ,1          53                        BO                       •  H-"    l«'l  |-l«m-   (r«rh).  with  fJ,rk  .                                      T       8 

Rodder,  complete  «iih  f«hri<-  .78 

,  Kli-vatdr.  coinplrtr,  with  Mngr  dipt  and  faltrtr                  I  '      0 

Serrto    .,-.l.,.K   (lu-.^ht   at   wind,  ,-l.mb  is   100  feet  ,HT  Hni  ,,„„,,,,.„.;  wi,'h  f.,irlc 

,  13,500  ft.  ,irr  M-rtion   >trul    .                                                             .97 

aliMiliitr  i-riliiii;,   Ili.OOO  ft.  Straijrtit  orntrr  •x-i-tinti   slrul                                        3       i^ 

(.r,  .it.xt    hci.nlit    r.adi.d.    U.SOd    ft.    in    IU    ininiit. •-,    K>  rnilrrrarrla((r.    rcmiplrtr     wilh     >trut»    and    l.r.rinK, 

.  (js  whrrN,   tyrr-,  mill   shock   aliMirlirrs I0i       0 

Sliix-k  »hvirl>rr   (innltipli-  mil  »priii)r  t\pr).rarh    ....        4       0 

Stability  and  Controllability  £Z!**L?£  *""*'"  *"'"'""  **** 

\\  ncrl,   w ii n   IV  FT    .  o       4 

Hat,   of  ,.,„„,,  a,  IU.  height,  ,„  f,,t  ,,,r  .inute.  31^-5 ^^S-«                                    ^    " 

!u>  ina.-liMir  caim..)   be  considered  vteble.     There  is  WinKS.  trailing  .,,,,r.  ,HT  foot  run  o    14% 

a  tendency  to  stall  with  thr  mjiine  on,  and  to  dive  with 

tin-    ,  iinin.     ,,tl.      Din  .-tionallv.    owing    to    tin-    propeller  Historical  Note 

s«,rl.  thr  ,,,;,,.|,i,,,.  swings  to  the  left,  but  with  thr  ni,{iiii-  The  pr.-s.-nt  H.-,ll.,-rst,,lt  fightrr  is  .-,  <l.-i.-1»pim-iit  of  the 

ls  '"  "tri1  enrlirr   sin^l,   s.-nter.   an   example   of  which   wax   brouglit 

!».rt  th.    m.-u-hi,,,.  |j£ht  and  comfortal:],    to  fly.  down  on  October  ii<».    I!»IT.      In   th.-   latt.-r  «-»>e  ash  was 

'M.-.nralMlity    is   KO,H|.   and    this    fraturc.   tak.-n    in  lls,.,|    ,,,  „    f,irlv   |nr)f<.   ,.xt,.,lt.   U.th    in   the   fuselage   and 

njmu-ti,,,,  with  th.-  exceptionally  tin,-  vi.-w  ..f  thr  pilot  will>INi  f)llt   in   j|1(.  m,,r(.  ln,Mj,.rn  (|,.s^n   ,priu.,.   is  (.xoiu. 

bterra  an,!  thr  h'.-hl  of  fire  of  the  latter,  makes  thr  siv,.|v  ...L.pted.      Thr  r.-.-ir  spar  was  of  thr  ordinary   ' 

irhin,   oti,-  to  !„•  r.-.-konrd  with  as  a  "  two  s,  at,  r  fighter."  (ion  type  without  three-ply  rrinforerment.      Thr  fuselage. 

^h    the    climb    and    speed    performances    are    poor  ,,f  somewhat  similar  shapr,  was  fabri,   ,,,v- r,d.      Balanced 

Hpd    by    ..-ntrmporary    British    standards.  elexators    and    rudder    were   fitted,   but    no    fixed    tail  plane 

or  fin.     Tli,    arrangement  of  the  centre  section,  with  tank 

rincipal  Points  of  the  Design  and  radilllor>   w;ls    M1|1,l.1Iltial|v   „„.   s»m,..      |,011|,i,.   h.^, 

-     _lr  bay  arrangements  of  wings.  of   interplanr    struts   were   adopted,   but    thr   struts   tin  m 

iiieuoiis  set  back  of  thr  main  planes.  sdves  were  of  the  welded-up  ta|«-red  pattern.     The  ailer- 

Bmpennage  fre>-  from  wir,v  ons   were  controlled   by   wires  and   not.  as   in   the   prrvnt 

I 'iisilage  ta|MTs  to  a  horizontal  line  at  the  rear  in  di-  example,  positm-ly.      Both  planes  had  the  same  chord  and 

•utradistinetion  to  the  usual  (,,  rinin  practice.  the   upper   wings    had   an   overhang.      The   weight   of   the 

Pilot's  and  observer's  cock-pits  constructed  as  one.  complete  machine  without  pilot  was   17*8  Ibs. 


\  /      i; 
_..,,_,,•-..._.,--,. 


AUSTRIAN  TYPE  ALBATR05 

HAN5A   BRANDENBURG 

^00  H-P   FIGHTING  TRACTOR 


MILLIMETERS 

ItOO  tOOO  I 


Mclaughlin 


194 


SINC.I.K  MOTOK1.I)  AEROPLANES 


The  German  Hansa-Brandenburg  Tractor 


Tin-  struts  st.-iiifjercd  outward  at  their  lower  rnd-.  is  a 
ttatiirc  peculiar  to  this  machine.  Many  of  tin-  Albatros 
features  art1  sci  n  in  this  machine,  together  with  a  mini 
lx-r  i>f  original  and  unique  fittings.  Tin-  accompanying 
drawing-,  show  a  side  and  front  vii-w  and  a  plan  vn  « 
from  In-low . 

General  Dimensions 

Sp.m,    ii|i|irr   plane    l-.i40  nun. 

Span,  low  IT  plain-    II. 7  .'n  nun. 

Cliortl.   I  .illi    planes    l,7i:l  nun. 

Area,  iipprr    plain-    ^."70  M).   ini-lrr-.. 

Area,   lower    plain-    1,790  v|.    meters. 

(l.ip  lu-twt-cii   planes    1,7  l:i  nun. 

(Kcrall    hcicht     ..I  I  'nun. 

Overall    length     8,370  mm. 

M,.t..r.   \V.ir-k:ilowski    **>  h.p. 

Planes 

Plain-,  arc  in  four  sections  two  upper  and  two  lower. 
l'|i|n-r  pi. me  M -etions  joined  at  tin-  top  of  a  cabane  formed 
of  steel  tube  :io  liy  Hi  mm.,  with  lower  ends  terminating 
in  fittings  attarln-d  to  tin-  upper  longerons  of  the  fuselage. 

F.ach  upper  plane  section  has  an  area  of  1135  sq.  meters. 
F.ach  lower  plane  section  has  an  area  of  895  sq.  meters. 

Ailerons  are  attached  to  subsidiary  steel  tube  spars  to 
the  rear  of  the  main  wing  beams.  Attachment  is  made 
with  a  fitting  of  sheet  metal  and  soft  wood  blocks,  with 
tiler  to  take  up  the  wear.  Kach  aileron  has  five  such 
hinges.  Ailerons  each  2850  mm.  long. 

Wing  beams  arc  cut  in  two  vertically,  hollowed  for  light- 
ness and  mortised  together  with  hardwood  strips.  For- 
ward .spar  varies  from  70  to  72  mm.  in  height  and  the 
rear  spar  the  opposite;  both  are  85  mm.  thick. 

Filtering  edge  is  curved  to  a  diameter  of  Ml  mm.  Front 
spar  centered  100  mm.  from  leading  edge.  Wing  spars 
SIMI  mm.  apart. 

Halt. us  are  ->.:>  thick  and  13  mm.  wide.  Webs  45  mm. 
thick,  cut  away  for  lightness  to  within  15  mm.  of  the 
battens.  Light  veneer  strips.  12  mm.  wide,  reinforce  the 
weds  between  lightening  holes. 

The  interplane  struts  are  of  32  mm.  diameter  steel  tube 
with  their  ends  terminating  in  eyes  for  attachment  to  the 
strut  sockets.  Hollow  wood  fairing  strips  are  bound  to 
tin-  rear  of  the  strut  tubing,  giving  it  a  streamline  form. 
and  bringing  its  width  to  126  mm.  Each  end  is  attached 
by  an  s  mm.  bolt.  Lift,  landing  and  incidence  cables 
vary  from  5  to  7  mm.  in  diameter. 

Fuselage 

Overall  width  of  fuselage,  1020  mm.  From  the  for- 
ward engine  plate  to  the  rudder,  the  fuselage  is  7180  mm. 
long.  A  formed  cap  fits  over  the  forward  engine  plate, 
and  the  propeller  shaft  goes  through  it.  Four  sheet  metal 
engine  plates  carry  the  two  50  by  100  mm.  engine  bed 
rails.  The  longerons  are  solid,  80  by  45  mm.  at  the 
front,  the  lower  pair  tapering  to  19  mm.  square  and  the 
upper  pair  17  mm.  square. 

The  pilot's  seat  is  set  in  a  recess  formed  at  the  top  of 
the  main  fuel  tank.  Overall  dimensions  of  the  tank  — 
top  300  by  820  mm. ;  bottom  "OO  by  82(1  mm. ;  height  650 
mm.  The  back  forms  a  right  angle  with  the  top  and 


liottoin  and  the  forward  end  slopes  down  from  the  top. 
A  recess  1711  nun.  .|,.|..  71111  .mn.  long  and  t?(l  mm.  w nit- 
is  proxided  for  the  seat.  Seat  :>.MI  mm.  long  and  UO  mm. 
wide,  rcsimg  on  n  pair  of  iron  bands  ~ :.  mm.  thick  and  31 
mm.  wide,  which  encircle  the  tank.  A  tilling  tulx-  runs 
up  at  the  rear  of  the  tank,  mar  the  .side,  with  n  :>  I  nun. 
opening. 

A  fixed  machine  gun  is  provided  for  the  pilot,  located 
on  the  upper  plane.  The  ^miner's  cockpit,  at  the  rear, 
is  provided  with  a  movable  machine  gun  clamped  to  a  rail 
around  the  cockpit  o|x-ning. 

Tail  Group 

Tin-  horizontal  stabilizer  is  in  one  piece,  resting  on  the 
upper  longerons.  The  forward  end  is  rounded  off  at  a 
HIM  mm.  radius.  Overall  dimensions,  229(1  by  ••.'!> M)  mm. 
Surface  at  each  side  of  body,  192  square  meters.  Tin- 
edges  are  of  steel  tube  20  mm.  in  diameter  and  the  in- 
ternal structure  is  of  10  mm.  diameter  tulx-.  It  is  sup- 
ported from  IM-IHW  l>y  a  pair  of  steel  tubes  of  25  by  13.5 
mm.  section.  Threaded  eyes  in  the  lower  ends  allow  of 
their  adjustment.  Lower  ends  attach  to  lower  longerons 
at  a  point  1860  mm.  from  the  fuselage  termination. 

Slots.  GOO  mm.  apart,  are  provided  where  the  flap  con- 
trol cables  run  through  the  stabilizer. 

From  tip  to  tip  the  elevator  flaps  measures  3500  mm. 
Maximum  width,  670  mm.  Kach  flap  has  an  area  of  83 
square  meters.  Edges  are  formed  of  15  mm.  tube,  and 
outer  tips  curved  to  a  120  mm.  radius. 

Flap  hinges  are  of  sheet  metal,  soldered  to  the  25  mm. 
till"  of  the  flap  and  stabilizer.  Fiber  blocks  between  the 
tubes  space  them  10  mm.  apart,  and  take  the  friction  of 
the  flap  movement. 

The  vertical  fin  is  triangular,  700  mm.  high  and  13OO 
mm.  wide.  The  rudder  is  l<>'>(>  in  overall  height.  Width 
at  rear  of  pivot,  670  and  width  forward  of  pivot  (the 
balanced  portion)  340  mm.  Forward  edges  curved  to  a 
30  mm.  radius,  and  trailing  end  to  a  110  mm.  radius. 
Two  hinges  attach  the  rudder  to  the  fin.  The  control 
lever  is  of  solid  steel,  and  it  spaces  the  control  wires  117 
mm.  apart. 

Landing  Gear 

The  axle  is  of  steel  tube,  54  mm.  outside  diameter.  Mi 
mm.  inside,  located  at  a  point  1680  mm.  from  the  front 
of  propeller  hub.  Landing  wheels  are  770  mm.  in  diam- 
eter by  KM)  mm.  wide,  and  centered  2070  mm.  apart. 
Two  sections  of  streamline  fairing  are  bound  to  the  axle, 
and  a  claw  brake  between  them. 

The  brake  is  730  mm.  long;  230  mm.  forward  of  the 
axle  and  5OO  mm.  to  the  rear.  The  claw  is  145  mm.  in 
length,  and  the  brake  is  operated  by  a  cord  from  the 
pilot's  seat. 

The  chassis  struts  are  of  70  by  35  mm.  tube.  The  for- 
ward pair  is  faired  with  streamlining  to  a  total  depth  of 
120  mm.  A  peg  is  located  half  way  up  both  of  these 
struts  as  a  means  of  mounting  to  reach  the  motor.  At  the 
lower  end  of  chassis  struts,  the  shock  absorbing  elastic 
cords  are  bound.  Grooves  keep  them  in  place  and  a 
leather  strap,  strung  from  forward  to  rear  struU,  limits 
the  upward  movement  of  the  axle. 


Details  of  the  Hansa-Brandenburg  Tractor 
196 


SI\(.I.K   MUTOKKI)  AKKOl'I.AM  - 


197 


Details  of   the  Austrian   Hansa-Brandenburg  Tractor 

'< 


One  of  the  i  lrv.il, ir  rontrol  levers 


Rear  attachment  of  tin-  tnil  plain-  to  (lie  fuselage 


Tin-  t»n  fnrwar<l  engine  plates 


Strut  fitting  «t  the 
front  -.im r,  upper  left 
wlnjf 


I  runt,   side   and    top   views  of  the  main   fuel  tank,  upon 
whioh   tin-   pilot's  seat   is  plared 


Aileron    and    tail    flap    or 
stabilizer  hinges 


Ix)wer  end  of  the  brace  from  the 
tall  plane  to  the  fuselage 


198 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


I  'I  'I  '"I1  I'l  '  I  '1H  'i1  i>  t'  i't1  liU'Hji1  VH 


The  Wittemann-Lewis  Commercial  Biplane 


The  Wittemann-Lewis  Aircraft  Company  Model  "  F.  A. 
2  "  is  the  result  of  careful  planning  for  a  commercial 
airplane  by  the  Messrs.  Wittemann,  and  built  to  the  design 
of  A.  F.  Arcier,  A.  F.  R.  Ae.  S.,  formerly  chief  engineer 
of  Handley-Page,  Ltd.,  and  now  chief  engineer  of  this 
Company. 

The  principal  features  of  the  machine  are  the  unusually 
low  landing  speed,  the  large  capacity  and  sumptuousness 
of  the  body,  and  the  comparatively  small  space  in  which 
it  may  be  housed  by  folding  the  wings. 

Wings:  —  The  upper  wings  are  composed  of  three  sec- 
tions, the  lower  ones  of  four.  The  outer  sections  hinge 
back  by  simply  removing  four  pins,  when  in  the  folded 
position  they  clamp  back  against  the  fuselage.  The  spars 
are  I  section  spruce  and  the  ribs  special  built  up.  The 
interplane  struts  are  spruce.  The  main  spar  clips  are  so 
designed  that  they  set  up  no  additional  bending  mo- 
ments. 

Body: — The  L.  C.  Liberty  motor  is  silenced  and  is 
mounted  on  ash  beams  supported  by  tubular  construc- 
tion. The  whole  power  unit  comprising:  —  Propeller, 
Radiator,  Motor  and  Tanks,  is  removable  in  one  unit  by 
undoing  six  bolts  and  disconnecting  the  control  and  instru- 
ment leads.  Risk  of  fire  is  reduced  to  minimum  by  fire- 
proof bulkheads  and  by  suitable  placing  of  carburetors  in 
fireproof  compartments. 

Reliability  of  the  motor  is  assured  by  reducing  its  maxi- 
mum output  and  by  gravity  fuel  feed. 

The  cabin  is  approximately  5' 6"  x  4' x  9',  giving  170 
cu.  ft.  of  unobstructed  space,  and  has  seating  capacity  for 


four  passengers  —  comfortable  swivel  arm  chairs  and  a 
folding  table  are  provided.  The  exhaust  heating  and  the 
ventilation  can  be  adjusted  by  the  occupants.  The  en- 
trance to  the  cabin  is  large  and  within  stepping  height  of 
the  ground,  making  the  machine  as  easy  to  enter  as  the 
average  automobile. 

Pilot  has  unobstructed  view  and  is  seated  aft  of  the  main 
loads. 

Landing  Gear:  — •  The  landing  gear  has  an  exceptionally 
wide  track,  making  overturning  impossible,  long  travel 
shock  absorbers  are  fitted  and  a  dashpot  provided  to  pre- 
vent rebound.  These  precautions  together  with  the  low 
landing  speed  make  the  machine  very  safe  and  easy  to  land. 
The  tail  skid  is  steerable  on  the  ground  to  facilitate 
ground  manoeuvring. 

Controls:  —  A  "  Dep  "  arch  is  provided,  and  the  rudder 
is  operated  by  foot  pedals.  The  tail  is  adjustable  in  flight 
for  varying  loads. 

The  disposition  and  size  of  the  controlling  surfaces  are 
such  as  to  assure  a  large  degree  of  inherent  stability. 

Area:  —  Top  plane,  3S3  sq.  ft.;  lower  plane,  306  sq.  ft.; 
ailerons,  92  sq.  ft. ;  tail  plane,  70  sq.  ft. ;  tail  flaps,  20  sq. 
ft.;  rudder,  12J/6  sq.  ft.;  fin,  8  sq.  ft.;  chord  both  planes, 
6  ft.  9  in.;  gap,  6  ft.  0  in.;  span,  wings  extended,  52  ft.  0 
in.;  wings  folded,  22  ft.  6  in.;  o.  a.  length,  35  ft.  1  in.; 
o.  a.  height,  wings  extended,  11  ft.  0  in. ;  o.  a.  height, 
wings  folded,  9  ft.  9  in.;  weight  full,  4,040  Ibs. ;  useful 
load,  1,650  Ibs;  loading  6.33  Ibs.  per  sq.  ft.;  duration 
(cruising),  4'/£  hours;  landing  speed,  35  m.p.h. ;  top  speed, 
105  m.p.h.;  ceiling,  15,000  ft.;  climb,  10,000  ft.  in  30  min. 


ROLAND  D.n. 

16O  H.P 
MERCEDES. 


I  : 

1«cK- wop  " 


The  Kol«ml  Sin^k-«-.tcr  Ch^er  D.ll.     PUn,  »W<-  .nd  front  ele»thm.  to 

11)0 


200 


TKXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Starboard  quarter  view  of  the 
lioland  D.II.  chaser 


The  Roland    Chaser  D.  II. 


The  dimensions  of  the  Roland  D.  II  are  very  small: 

Span  of  upper  plane  8.90  m. 

Span  of  lower  plane   8.50  m. 

1  .ength  overall   6.95  m. 

Height      2.95  m. 

Its  weight  —  827  kilogs. —  with  full  tanks  is  slightly 
greater  than  that  of  the  Albatros  D.III  chaser.  The  lift- 
ing surface  being  23  sq.  m.,  the  wing  loading  is  36  kg./sq. 
m.  (7.2  Ibs./sq.  ft). 

Fuselage 

The  construction  of  the  fuselage,  and  its  peculiar  shape, 
merit  special  attention.  Being  built  entirely  of  three-ply 
wood  and  covered  with  fabric,  it  is  of  the  monocoque  type, 
of  oval  section,  and  terminates  at  the  stern  in  a  vertical 
knife  edge.  The  construction  is  excessively  light,  the 
framework  consisting  of  very  thin  longerons  running 
through  the  whole  length  of  the  body,  the  curves  of  which 
they  follow.  Rigidity  is  only  provided  bv  the  ply  wood, 
made  in  two  halves  joined  along  the  middle  of  the  top 
and  bottom.  The  total  thickness  of  the  six  layers  is  only 
1.5  mm.  From  the  pilot's  seat  to  the  tail  there  are  only 
four  formers  of  very  small  thickness. 

Between  the  pilot's  seat  and  the  motor  the  fuselage 
forms  a  projection  tapering  upwards  to  form  at  its  upper 
extremity  an  edge  0.11  m.  wide,  to  which  are  attached 
the  radiator  and  the  top  plane.  The  top  plane  is  cut 
away  to  accommodate  the  radiator.  This  arrangement 
of  an  upward  projection  of  the  body  itself  takes  the  place 
of  the  cabane.  On  the  lower  part  of  fuselage,  and  built 
integrally  with  it,  there  are  the  rotts  to  which  the  two 
halves  of  the  lower  plane  are  attached.  At  the  rear  the 
tail  skid,  of  wood  with  a  shoe  of  metal,  pierces  the  fuse- 
lage, and  is  supported  on  a  projection  of  ply  wood  similar 
to  that  employed  on  the  Xieuport. 

The  pilot  is  placed  very  high,  and  has  in  front  of  him 
two  wind  screens,  one  on  each  side  of  the  central  struc- 
ture carrying  the  upper  plane. 

Planes 

The  planes  are  of  trapezoidal  plan  form,  of  unequal 
span,  without  stagger  and  dihedral  angle,  but  with  a  sweep- 
back  of  1.5°.  The  chord,  which  is  uniform,  is  1.45  m. 
and  the  gap  1.3-1  m.  The  ribs  are  at  right  angles  to  the 
leading  edge.  As  the  inter-plane  struts  are  secured  to 
the  spars  over  the  same  rib,  it  follows  that  in  the  front 
view  the  struts  do  not  come  quite  in  line.  The  spars  of 
the  upper  plane,  which  are  of  spruce,  are  spaced  0.83  m. 


apart,  the  front  spar  being  0.13  m.  from  the  leading  edge. 
The  ribs,  of  which  there  are  12,  are  of  I  section  with 
flanges  of  ash.  They  are  spaced  about  0.37  m.  apart. 
In  the  middle  of  each  interval  there  is  a  false  rib  running 
from  the  leading  edge  to  the  rear  spar.  In  each  wing 
there  are  four  compression  members  in  the  form  of  steel 
tubes  25  mm.  diameter.  These  tubes  are  evenly  spaced, 
the  distance  between  them  being  1 .30  m.,  and  are  braced 
by  3  mm.  piano  wire.  Between  the  front  spar  and  the 
leading  edge  there  are  two  tapes  running  parallel  to  the 
spars  and  crossing  alternately  over  and  under  consecutive 
ribs.  Two  more  tapes  are  similarly  arranged  between  the 
spars.  Certain  corners  are  stiffened  by  reinforcement  by 
ply  wood.  Each  of  the  upper  planes  carries  an  aileron, 
which  is  not  balanced  and  of  equal  chord  throughout.  A 
strip  of  three-ply  wood,  under  the  fabric,  covers  and  pro- 
tects the  hinge  fixed  on  the  rear  spar.  The  aileron  meas- 
ures 1.82  m.  in  length  and  has  a  chord  of  0.42  m.  Its 
leading  edge  is  a  steel  tube  of  30  mm.  diameter.  The 
aileron  cranks  are  operated,  as  in  the  Nieuport,  by  two 
vertical  tubes.  In  the  left  top  plane  is  mounted  a  petrol 
service  tank. 

The  lower  planes  are  constructed  in  much  the  same 
manner  as  the  top  ones.  The  spars  are  similarly  arranged 
and  are  consequently  the  same  distance  apart.  In  each 
wing  there  are  10  ribs,  of  which  nine  measure  0.01  m. 
and  the  last  one  0.025  m.  Between  the  ribs  are  false  ribs 
measuring  10  mm.  The  internal  wing  bracing  is  the 
same  as  that  of  the  top  plane,  but  the  distribution  of  the 
four  steel  tube  compression  struts  (of  which  one  is  20 
mm.  and  the  other  25  mm.)  is  somewhat  different.  From 
the  first  to  the  second  is  1.17  m.,  from  the  second  to  the 
third  is  1.13  m.,  and  from  the  third  to  the  fourth  1.11  m. 
The  lower  planes  are  attached  to  wind  roots  built  in- 
tegrally with  the  fuselage.  The  angle  of  incidence  is  4° 
at  the  second  rib  and  3°  at  the  seventh.  The  interplane 
struts  are  in  the  form  of  steel  tubes  0.025  m.  diameter, 
stream-lined  with  a  wood  fairing  which  brings  their  depth 
to  0.09  m. 

The  Tail 

The  shape  of  the  tail  can  be  seen  from  the  plan  view 
of  the  machine.  The  fixed  tail  plane  is  built  of  wood, 
while  the  two  elevator  flaps  are  constructed  entirely  in 
metal. 

A  note  should  be  made  of  the  attachment  of  the  tail 
plane  to  the  body.  The  leading  edge  of  the  tail  plane  is 


SINCl.K    MOTOHI.I)   AKUOl'I.ANK.s 


•-•in 


II.     II..I...:!   D.I  I.  ,.|r,s,.r.      (1) 


of  "bump"  supporting  top  plnnr  nml  radiator.     (.')  <Juick-rrlcn>e  l>olt  for  HttH.liinif  main 
planes.     (3)    I'pprr  plane.     (4)  One  of  the  miiln  plane   rllw 


hollowed  out.  and  into  the  hollow  space  thus  formed  fits 
n  piece  of  wood  which  runs  across  the  fuselage  and  the 
ends  of  which  project  (1.50  m.  on  each  side.  Further 
rigidity  is  uivm  to  tin  structure  by  two  stream-line  tubes 
runnitifj  from  the  tail  plane  to  the  rudder  hinge  on  the 
•  I  fin.  The  rudder,  which  is  roughly  rectangular 
with  round, (1  corners  and  has  a  forward  projection  for 
l''il.-incing.  is  built  up  of  steel  tubes,  while  the  fin.  which 
is  made  integral  with  the  body  is  of  three-ply  wood. 

Engine 

The  engine  fitted  on  the  Roland   D.   II   is  a   160  h.p. 
(lea  six-cylinder  vertical  engine.     The  exhaust  col- 


Irctor  is  nearly  horizontal,  and  is  placed  on  the  starboard 
side.  In  addition  to  the  gravity  tank  in  the  top  plane 
there  is  a  main  gasoline  tank  measuring  70x70x25  un- 
der the  rudder  bar.  The  airscrew  has  its  boss  enclosed 
in  the  usual  "  spinner." 

Undercarriage 

The  undercarriage  is  formed  by  two  pairs  of  Vee  struts, 
braced  diagonally  by  two  crossed  cables.  Their  attach- 
ment to  the  fuselage  occurs  at  two  sloping  formers.  The 
axle,  which  is  placed  between  two  cross  tubes,  is  enclosed 
in  a  stream-line  casing.  The  track  is  1 .7.1  m.  The  wheels 
measure  700  by  100.  The  shock  absorbers  arc  of  rubber. 


Siile  view  of  the  fusehjre  of  the  Roland 

IHI      rli.'isi-r.     Tl mil     siw     of     this 

111:11  -liinr  is  apparent  from  the  picture. 


•20-2 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Comparative    specifications    of   the    L.    V.    G.   biplanes 
C.II.,  C.IV.,  C.V.,  and  Rumpler  C.IV.: 


L.V.G. 

Rumpler 

Span  (upper  wing) 
Span  (lower  wing) 
Total  length  
Height  

C.II. 

12.85m. 
11.35m. 
8.10m. 
3m 

C.IV. 

13.60m. 
13m. 
8.60m. 
3.10m. 

C.V. 

13.62m. 
13.85m. 
8.10m. 
3.90m. 

C.IV. 
12.60m. 
12.10m. 
8.4m. 
3.25m. 

Lifting  surface  .  . 
Weight  

37.60sqm. 
845kg. 

40sqm. 
900k  g. 

42.70sqm. 
930kg. 

33.50sqm. 
1,010kg. 

Power  of  motor  .  . 
Make  of  motor  .  .  . 

175h.p. 
Mercedes 

235h.p. 
Mercedes 

225h.p. 
Benz 

260h.p. 
250h.p. 
Mercedes 
or  Maybach 

Note  — 1  metre  =  32.37  inches. 

1  sq.  metre  =  10.75  sq.  feet. 
1  kilogramme  =  2.2  Ibs. 

The  L.V.G.  type  C.V.  is  a  two  seater.  It  belongs  to 
the  "  general  purpose  "  class. 

Less  speedy  on  the  flat  than  the  Rumpler  C.IV.,  its 
rate  of  climb  is  inferior  (4000  metres  in  35  minutes),  and 
equally  its  ceiling  is  less  elevated  (a  little  more  than 
5000  metres). 

Its  speeds  are  as  follows : 

At  2,000  metres   164  km.  per  hr. 

At  3,000  metres    160  km.  per  hr. 

At    4,000    metres    150  km.  per  hr. 

The  Wings 

The  upper  and  lower  wings  are  set  at  a  dihedral  angle, 
more  so  the  lower  ones. 

This  dihedral  is  of  1°  to  the  upper  wings  and  of  2° 
to  the  lower.  They  are  neither  staggered  nor  swept  back. 


Front  view  of  the  L.V.G.  biplane:  type  C.V. 

The  L.  V.  G.  Biplane  Type  C.  V. 

The  trailing  edges  of  the  wings  are  flexible.  The  ribs 
are  spaced  about  .4  m.  apart,  with  false  intermediary  ribs. 
The  incidence  of  the  wings  is  as  follows: 

At  1st  and  2nd  ribs 4.5° 

At  3rd  to  9th  ribs   5° 

At  10th  rib   4.75° 

At  llth  rib   -I -5° 

At  12th  rib  4° 

At  13th  rib   3° 

The  upper  wings,  viewed  in  plan,  are  slightly  trape- 
zoidal, with  rounded  edges. 

Their  chord  is  1.74  m.,  and  in  the  centre  a  semi-circular 
piece  is  cut  out  of  the  trailing  edge  above  the  pilot's  head. 

The  ailerons  project  past  the  ends  of  the  wings  by  .84 
m.  Their  form  is  rounded,  and  resembles  that  of  the 
ailerons  of  the  Gotha.  Their  total  length  is  2.61  m. 
Their  chord  varies  from  .53  m.  inside  to  .75  m.  at  the 
projecting  portion. 

The  hinges  of  the  ailerons  are  parallel  with  the  lead- 
ing edge  of  the  wing.  They  are  attached  by  means  of 
pins  or  bolts  threaded  through  hinge  loops,  held  in  place 
by  keys,  on  the  system  employed  to  attach  the  ailerons 
on  the  Roland  fighter  D.II.  The  arrangement  has  the 
advantage  of  permitting  the  quick  attachment  of  the  mem- 
bers. 

The  lower  wings,  following  the  present  tendency  of 
German  aeroplanes  are  rounded  at  the  ends  and  taper  at 
the  rear,  as  in  the  D.F.W.,  Rumpler  C.IV.,  and  Albatros 
C.IV.  Their  maximum  chord  is  1.59  m. 

The  aileron  cables  pass  through  the  interior  of  the 
lower  wings. 

The  interplane  struts  (two  pairs  on  either  side  of  the 
fuselage)  are  constructed  of  streamline  timber  105  m.  in 


Rear  view  of  the  L.V.G.  biplane:  type  C.V. 


S1NCI.K   MOTOKK1)   A  I  .K<  >1'L.\  M  .x 


\     \ii-w     nf 


tail    inrnilirrs 


(lianu-tcr.  and  t.-ipiTnl  towards  Imth  i-iuls.  Bv  reason  of 
tin-  differing  dihedral  of  angles  the  inside  and  outside 
struts  :irr  not  thr  same  length. 

Tlii-  outer  struts  are  1.6.S5  m.  long  and  the  inner  ones 
I.:.!"  in. 

Tin  gap  between  thr  wings  is  1.71  m.  at  tlie  fuselage 
.-iixl  I  t'lii  in.  in  linr  with  thr  rxtrrn.il  struts. 

Thr  total  lifting  surface  is  i  j  ;i  M|.  m..  that  of  the  up- 
per plain-  hriii^  -.':!.  7S  sq.  m.,  and  the  lower  19.17  sq.  m. 

Tin-  rah.-nir  struts  an-  in  thr  form  of  an  "  N."  inclined 
towards  tin-  ri  ar.  and  converging  to  the  fixed  centre  sec- 
tion of  thr  upper  plane,  tin-  width  of  which  is  .IS  m. 

The  Tail 

Tin-  sh.-ipr  of  tin-  stabilizing  plane,  or  fixed  tail  plane, 
resembles  that  of  the  Albatros  fighter. 

Thr  tail  plane  consists  of  two  separate  parts  attached 
our  on  each  side  to  a  fixed  section  embodied  in  the  fuse- 
which  like  it  is  constructed  of  three-ply. 

Thr  elevator  is  a  single  flap,  with  rounded  corners  and 
balanced  by  a  triangular  extension  at  each  end.  The 
•  test  width  is  :i.(H  m.  and  the  depth  .65  m.  The  small 
triangles  have  a  base  of  .39  m.  and  are  .39  m.  high. 

At  the  outer  angle  of  each  of  the  tail  planes  one  finds 
a  projection  of  about  .040  m..  intended  to  eliminate  vi- 
bration from  the  tips  of  the  balanced  ends  of  the  eleva- 
tors by  screening  them  from  the  air  blast. 

The  balanced  rudder  is  placed  above  the  elevator,  and 
forms  with  the  fixed  fin  an  oval  inclined  backwards. 

Tin-  fixed  fin  is  constructed  of  -three-ply,  and  is  trape- 
•oidal  in  shape.  The  total  height  of  the  vertical  empen- 
nage is  1.068  m.;  its  depth  is  .675  m.  (1.15  m.  including 
tin  compensated  portion). 

The  internal  structure  of  these  members  consists  of  steel 
tube-work. 

The  control  cables  pass  through  the  fuselage,  coming 
outside  l.."i()  m.  from  its  extremity;  one  pair  of  the  ele- 
vator cables  pass  through  a  channel  in  the  thickness  of 
the  stabilizing  plain  . 

The  fuselage  is  entirely  built  of  varnished  three-ply, 
and  is  rectangular  in  form,  with  a  well-rounded  top.  the 
uiuii  rside  being  slightly  less  rounded.  The  sides  have 
a  slight  outward  bulge,  accentuated  at  the  level  of  the 
pilot's  seat. 

The  Power  Plant 
The  I..V  (  .     i    \   .  is  driven  by  a  Garuda  airscrew,  type 


A  view  of  the  rvlmiist    in.iiiifoM 

V.,  with  a  diameter  of  .S.oi  m.     The  boss  of  the  airscrew 
is  enclosed  in  a  "  Casserole,"  or  pot.  .58  m.  diameter. 

The  motor  is  a  225  h.p.  Hen*,  also  used  in  the  D.I   \\ 
and  F.1XH.G.  II. 

It  is  fed  by  two  tanks,  with  a  capacity  of  249  litres. 
On  the  upper  left  wing  is  fitted  a  feed  tank.  The  con- 
tents of  these  tanks  permit  of  a  flight  of  almut  3'  ,  hours. 

Tin  up|M-r  portion  of  the  motor  is  entirely  covered  in 
with  a  panelled  and  removable  sheet  steel  bonnet. 

The  exhaust  is  led  overhead  as  in  the  Kumpler  ('.  IV. 
Contrary  to  that  machine  it  is  not  much  curved,  but  rises 
nearly  vertically. 

The  honeycomb  radiator,  the  capacity  of  which  is  35 
litres,  is  placed  in  front  of  the  wings.  It  is  rectangular 
in  shape,  and  is  attached  to  the  eabanc  struts  by  two 
brackets.  Its  upper  part  is  attached  to  the  fixed  centre 
section  of  the  upper  plane  by  a  small  steel  tube  fork. 

Tin  temperature  regulating  blind  placed  in  front  of 
the  radiator  is  one  of  the  best  in  use.  It  is  simpler  and 
more  rational  than  the  system  of  shutters.  It  consists 
of  a  movable  blind  of  strong  fabric,  which  is  rolled  and 
unrolled  at  the  will  of  the  pilot,  which  permits  the  stop- 
page of  the  passage  of  air  and  the  regulation  of  the  cool- 
ing. 

Accommodation 

The  accommodation  for  the  pilot  is  of  oval  form,  the 
bigger  dimension  being  in  the  direction  of  travel. 

Very  close  to  this  is  arranged  the  passenger's  seat  in- 
side a  turntable  .86  m.  in  diameter,  which  carries  a  "  Para- 
belltim  "  machine-gun. 

In  front  and  on  the  right  side  is  a  Spandau  machine- 
gun  firing  through  the  airscrew,  and  controlled  by  a  Bow- 
den  wire. 

Wireless  apparatus  is  installed. 

The  landing  carriage  consists  of  two  pairs  of  streamline 
"  V  "  struts  built  of  timber,  and  a  pair  of  wheels  810 
mm.  x  1 '2!>  mm. 

The  wheel  track  is  1.98  m.  The  axle  is  placed  in  a 
streamline  wooden  fairing. 

As  in  the  Rumpler  ('.IV.,  a  drag  cable  runs  from  tin- 
front  of  the  fuselage  to  the  base  of  the  inner  interplanc 
strut. 

Tin-  tail  skid,  which   is  attached  to  a  small  fin  uinl.  r 
neath  the  fuselage,  is  const  ructed  of  wood,  and  i»  termi- 
nated by  four  steel  laminations  ,«M)<  m.  thick. 

The  skid  is  sprung  with  elastic  cord. 


The  Ace-Motored  Single  Seater  Ace  Biplane 


The  small  light,  economical  single-seater  ACE  Biplane 
has  been  designed  to  answer  certain  requisites  as  follows: 

Its  wing  spread  of  only  28  ft.  4  in.,  overall  length  of 
1 8  ft.,  and  7  ft.  height  insure  a  very  small  and  economical 
hangar  for  housing  and  workshop  facilities.  It  is  strictly 
a  one-man  machine,  not  only  in  flying  but  in  being  handled 
on  the  ground  as  well,  as  one  man  can  pick  up  the  tail  and 
easily  pull  the  machine  into  the  hangar  alone  without  aid 
of  mechanic  or  extra  help,  because  of  its  lightness. 

The  performance  of  the  ACE  embodies  the  best  assets 
of  commercial  aviation,  such  as  a  quick  take-off,  fast 
climb (  wide  range  of  flying  speed,  slow  flat  glide  with  a 
twenty-five  mile  per  hour  landing  speed  and  a  very  short 
roll  which  averages  about  sixty  feet  after  the  wheels  touch 
the  ground. 

To  the  above  qualities  are  added  the  items  of  moderate 
cost  and  upkeep.  The  selling  price  being  $'2,500  places 
the  machine  well  within  the  reach  of  any  pilot  and  the 
maintenance  is  one-third  that  of  the  average  aeroplane. 
Gasoline  consumption  is  under  five  gallons  per  hour  and 
with  a  twelve  gallon  tank  one  has  a  cruising  radius  of  two 
and  one-half  hours. 

High  grade  construction  is  the  first  requisite  which 
proves  itself  in  giving  a  factor  of  safety  of  over  8.  An- 
other feature  is  the  short  space  of  time  in  which  the 
machine  can  be  assembled,  due  to  the  self-aligning  fixed 
strut  construction  which  eliminates  the  necessity  and  ex- 
pense of  an  expert  aeroplane  mechanic. 

The  machine  has  been  designed  with  the  idea  of  it  being 
used  not  alone  as  a  single-seater  sport  plane  but  for  com- 
mercial purposes  as  well;  such  as  carrying  mail,  light  ex- 
press, advertising,  exhibition  work,  and  to  be  used  by 


•204 


aerial  police  forces,  etc. 

In  recent  test  flights  one  hundred  and  eighty  pounds 
of  sand  was  carried  in  the  spare  space  of  the  machine,  in 
addition  to  a  full  load  of  fuel  and  the  pilot.  No  notice- 
able depreciation  in  climbing  was  observed.  This  speaks 
well  for  the  efficient  design  and  proves  that  the  machine 
can  carry  extra  weight. 

The  machine  was  tested  out  at  the  ACE  Flying  Field, 
Central  Park,  L.  I.,  by  the  Company's  test  pilot,  Bruce 
Eytinge,  formerly  a  First  Lieutenant  Instructor  and  Test 
Pilot  in  the  Royal  Air  Force  for  18  months.  On  the  first 
altitude  test  a  height  of  6000  feet  was  reached  in  20  min- 
utes and  later  8000  feet  was  reached  in  28  minutes.  Per- 
fect stability  and  height  climb  were  observed  at  this  alti- 
tude. On  flying  level  the  throttle  was  retarded  50  per 
cent,  and  the  machine  proceeded  in  straight  horizontal 
flight  flying  level  on  half  the  motor's  r.p.m.'s.  When  the 
throttle  was  entirely  retarded  idling  the  motor  the  ma- 
chine nosed  down  into  a  slow  flat  glide. 

Other  tests  of  the  machine's  speed  show  that  with  full 
throttle  it  is  capable  of  65  m.p.h.  In  testing  the  gliding 
quality  the  pilot  began  a  glide  from  an  altitude  of  8000 
feet  over  Mineula  at  a  distance  of  about  8  miles  from 
the  flying  field  and  continued  in  the  glide  past  his  field  to 
Amity ville.  a  distance  of  about  a  11  mile  glide  and  then 
turned  back  to  glide  into  the  airdome.  In  this  maneuver 
a  time  of  1 5  minutes  elapsed  before  the  ground  was 
reached  and  a  landing  was  made  about  20  feet  from  the 
hangar  with  a  dead  motor.  The  above  test  shows  that  in 
case  of  a  forced  landing  from  an  altitude  of  about  3000 
to  1000  feet  the  pilot  will  have  ample  time  to  select 
landing  field  within  a  radius  of  10  miles. 


SI\(,I.K  MOTOKKI)  AEROPLANES 


The  Ace  in  Hight  and  after  dim    bing  to  8000  feet  in  M  minutes 


Safety  Factor 

Selected  \\Ysteni  spruce  is  used  for  all  principal  parU 
of  wings,  struts  and  fus< -lagc.  etc.  The  complete  whiff 
structure  iiiuler  a  sand  load  test  have  supported  in  excess 
of  ten  times  the  weight  carried  in  flying.  Flying  tests 
have  shown  a  high  factor  of  safety  under  difficult  condi- 
tions of  /.ooming.  tail  slide  and  whip  stall,  loops,  spinning 
nose  dive,  inuncrinan  turns  and  falling  leaf.  etc.  The 
inai-liine  is  so  designed  that  it  has  great  inherent  stability 
and  if  the  controls  are  released  when  stunting  the  machine 
will  right  itself  from  any  position. 

Assembling  Facility 

One  does  not  have  to  be  an  expert  aeroplane  mechanic 
to  tinerate  and  assemble  the  ACK  Biplane.  This  item  is 
expediated  by  the  employment  of  only  two  flying  wires, 
two  landing  wires,  two  drift  and  two  anti-drift  wires,  and 
two  drift  struts.  The  fixed  stagger  and  angle  of  inci- 
dence are  obtained  through  the  employment  of  special 
single  self-aligning  struts.  The  lower  planes  have  a  3 
dihedral  angle  while  the  upper  planes  are  neutral. 

General  Specifications 

Span,  upper  plane   Jfl  ft.  4  in. 

I-enjrth.    overall    1H  ft. 

I  l.-i|rtit,   overall    7  ft.  6  in. 

Wheel   tread    60  in. 

\Vhtfl   iliiunrter    36  in. 

Siie  of  tire  i6  in.  x  3  in. 

Controls 

Lateral  and  longitudinal  balances  are  operated  by  stick 
•ontrol.  The  rudder  is  ojx-rated  by  a  foot  bar.  All  con- 
Ilinir  surfaces  are  large  and  balanced  affording  ease  of 
itrol  and  the  response  is  so  immediate  as  to  require  but 
i  slight  movement  of  the  control  stick  or  rudder  bar.  All 
•nntrol  wires  are  assembled  in  duplicate  seta. 

Fuselage 

The  fuselage  is  of  good  streamline  form.      It  is  of  War- 
ren-truss construction.      The  cockpit   is  of  3  ply  veneer. 
•  I  age   is  braced  with  piona  wire   from  the  pilot's 
kpit  forward,  and  with  T  section  struts  diagonally  stag- 
gered from  the  cockpit  rearward,  eliminating  all  wires  and 
The  motor  and  members  bearing  heavy  stresses 


are  attached  to  a  substantial  pressed  steel  nose  plate. 
The  motor  is  bolted  directly  to  the  plate,  and  by  eliminat- 
ing engine  beds  every  part  of  the  motor  is  immediately 
MCeadbfe.  This  is  the  most  rigid  motor  mounting  ever 
furnished  in  any  aeroplane  ami  the  absence  of  vibration 
is  a  noticeable  feature.  The  nose  is  covered  with  alumi- 
num, the  hood  being  arranged  in  quick  detachable  sections 
giving  easy  access  to  the  motor.  The  remainder  is  eo\ 
ered  with  linen,  doped,  colored  and  varnished.  The  body 
tapers  to  the  rear  on  which  the  double  cambered  rudder  is 
hinged.  On  the  instrument  Imard  in  the  cockpit  to  the 
pilot's  left  is  the  ignition  .switch  and  choke  wire,  to  his 
right  is  the  gasoline  throttle  and  in  the  center  an  oil  pres- 
sure gauge,  radiator  thermometer,  a  revolution  counter 
and  an  altimeter  to  indicate  height. 

Landing  Gear 

The  chassis  is  of  the  ordinary  V  type,  each  V  con- 
structed from  one  piece  one  inch  tubing.  Elastic  chord 
shock  absorber  binds  the  axle  to  the  struts.  An  under- 
carried  skid  of  hickory  fastened  to  the  center  of  the  nxle 
and  braced  with  two  streamlined  tubular  struts  prevents 
the  nosing  over  and  eliminates  the  ever  present  danger  of 
damage  from  overturning.  In  landing  the  tail  of  the  skid 
acts  as  a  brake,  bringing  the  machine  to  rest  after  a 
very  short  roll  of  about  6<)  feet.  This  feature  makes  the 
machine  the  safest  and  most  suitable  for  small  fields. 

Tail  Group 

The  tail  plane  is  a  fixed  stabiliser  of  single  cambered 
surface  to  which  is  hinged  the  balanced  elevator  flaps. 
The  vertical  fin  is  a  fixed  stabiliser  of  double  camber  to 
which  is  hinged  the  balanced  rudder.  The  large  bal- 
anced controlling  surfaces  and  the  undercarriage  skid 
make  this  machine  the  easiest  and  safest  to  taxi,  as  OIK 
can  easily  taxi  in  a  straight  line  or  make  a  turn  in  a  very 
small  space. 

Motor  Group 

An  ACE  four  cylinder  sixteen  valve  head.  4O  h.p., 
water-cooled  motor  is  used.  The  motor  has  been  so  care- 
fully balanced  as  to  entirely  eliminate  vibration.  Its 
weight  is  146  Ibs.  The  cooling  system  is  Thcrmo-svphon 
with  ample  water  capacity.  A  five  foot  pro|>cllcr  is 


206 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


A  skeleton  view  of  the  "Ace,"  showing  construction 


driven  direct  from  the  crank  shaft  at  2000  r.p.m.  A 
spinner  is  used  on  the  propeller  over  the  hub  and  is  so 
attached  in  front  of  the  motor  so  as  to  form  with  the  rest 
of  the  body  a  perfect  streamline  with  low  head  resistance 
and  giving  a  very  neat  appearance.  The  Atwater-Kent 
battery  ignition  system  is  used  which  affords  ease  in 


starting.  Lubrication  is  full  force  feed  by  a  spur  ge; 
pump.  Gasoline  system  is  gravity  feed  from  a  12-gallo 
tank  in  front  of  the  pilot  and  separated  from  the  mote 
by  a  fire  wall.  Zenith  carburetor  is  used  which  afforc 
economic  and  efficient  carburation. 


The  I.oening  Two-Sea 
er  Monoplane,  equippt 
with  a  :!00  h.p.  Hispan 
Suiza  engine. 


The   Bristol  Monoplane,  equipped  with  a  Le  Rhone  engine.     This  machine  has  a  wing  span  of  30  ft.  9  in.;  length  over  all  -20  ft 

4  in.;  chord  5  ft.  11  in.;  wing  area  145  ft. 


SIN(;i.K   MOTOKK1)   .\KHUIM..\\KS 


HANNOVFRANFR    B1P 

5PAN             

LANE. 
»  «• 

96'    Si- 
s'  I0r 

«    y 
f  r 

s    <r 

L  Jl] 

i 

g 

_^ 
1 

Lower  Plane         
CHORD          _ 
QAP-              (about) 
TAI1.PLANE    SPAN        ...  (Upperl 
...  (Lower) 
OVERALL    LENGTH        
ENGINE  (Opel-Arpu)    
PROPELLER 
TRACK          

5*                           iX 
ISO  H.P. 

9'    1"                            U 

f  tr                     \ 

N^ 

/-]  p  —  Zix^[ 

V  .               I 

"> 

^ 

/ 

The  Hannoveraner  Biplane 


M ncrallv  s|»  akin;;,  the  construction  is  of  wood  through- 
lit,  si,,  1  hcing  Use,l  sparingly,  except  in  the  intcrplanc 
truts.  landing  chassis  struts,  c. •ntn-  section  and  some  de- 
•iils  of  the  tail. 

The   construction    throughout   is   sound,   and    the    finish 
uit<-  i;ood. 

Tin    performance-  of  the  ni.-iehine  is  good. 

The  leading  particulars  of  the  plane  arc  as  follows: 
Vci^ht.    Kmpty.    l.?:l.'   |li>. 
nt.-d   Weight.  .',-.;.'  His. 
rr.-i  of  Ipp.-r  Winers.  _>|7.(i  si|.  ft. 
ir.-.i  ,if  I.,, WIT  Wiiijfs,   H_>.J  sq.  ft. 
nl. -i I    \re;i  ul    \Viri(rs,  Hiid.o  S(|.   ft. 

ilin^  pi  r  s.|    ft.  of  \Viti(t  Surfnee,  i.Jfl  Ihs. 
irrn  of  Aileron,  each.   lli.J  MJ.  ft. 
irrii  of  Hiiliinee  nf  Ailrnin.  l.fi  M).  ft. 
iren  of  Top   Pl.un-  or  Tail,  KM)  si|.  ft. 
n-;i  of  It, .11, MM   Hum-  of  Tail,  !!!..'  s<|.  ft. 
il    Vr.Ni  of  Tail  Plane,  .»»..>  s«|.  ft. 

i   Kin,  (i.j  sq.  ft.  approx. 
rca  of  Kiiil.lrr.  li.t  sq.  ft. 

•f  Kleuitors,  J.'.o  si|.  ft. 
lori/ont.il    \n-;i   of   |liHly.  .VJ..'  sq.  ft. 
<-rtii-;il    \rra  of  Body.  II I. li  -n.  ft. 
•  till   \Veifrht   prr  h.p.,   H.U  His.   p(-r  h.p. 
re«.   Pilot    mid  Ohscrver. 

riii.Hiient.   1    Spanclnu   Orin^  throiifrfi  propeller.     1   Pcrnhellum 
mi   rinjr  mounting. 

fini-.  (ipi-l    \r^ns.    I  MI  h.p. 

rtrol  Capacity,  :(7  >  ,    jrallons. 

•••ity.  :i  Dillons. 

Performance 
•  )   Climb  to  i,000  feet,  1  min-.. 

Rate  of  climb  in  ft.  prr  mln^  490. 


ln<licat<-<l  air  sprrcl.  6«. 

Hi-volutions  of  Kn^iiif,  l.lfi;,. 
(I))  Climb  to  Kl.(HM)  ft..  Is  mins. 

Hull-  of  climli  in   ft.  p,-r  min..  340. 

Imlieati-il   air  spc<-<l,  64. 

Hrvoliitions  of  Kiipinc.  1. 17.1. 
(c)  Climb  to  l:l.(HKl  ft..  .><l  mii,s..  f, 

Hate  of  dim))  in   ft.  p<-r  min..  |!»u. 

Indicated  air  speed,  (i.>. 

Kcvolutions  of  Knjrinr.  1,444. 

Speed 

At   10,000  ft.  96  miles  an  hour;  Revolutions,  1,464. 
At    13,000  89'/z  miles  an  hour;   Revolutions.   l.:,_><>. 
Service  ceiling  at  which  rate  of  climli  is   loo  ft.  p,-r  mi,,.,  U.OOO. 
Kstimateil  absolute  ceilinfr,  16,400. 
Greatest  heifrht  reached,  M.MHi  in  :t;i  n,ii,s.  in  sees. 
Hate  of  climb  at  Ibis  beipht,  IJO  ft.  per  mill. 
Air  endurance,  nlnnit    .'•_.   hours  nt   full   sprr«l   at    |(i,(HK)  ft.,  jn. 

cludiii);  climb  to  this  height. 
Military  load.  444  Iba. 

The  machine  is  nose-heavy  with  the  engine  off.  and 
slightly  tail-heavy  with  the  engine  on.  It  tends  to  turn 
to  the  left  with  the  engine  on. 

The  machine  is  generally  light  on  controls,  except  that 
the  elevator  seems  rather  insufficient  at  slow  sp.-cds.  It 
ia  not  very  tiring  to  fly.  and  pulls  up  very  (juicklv  on 
landing. 

The   view    is    particularly   good    for   hoth    pilot    and   oli 
server.     The  former  sit.s  with  his  eyes  on  a  level  with  the 
top   plane,  and   also   enjoys   a   good   view   below   him   on 
account  of  the  narrow  chord  of  the  lower  plane. 


208 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Rumpler  Two-seater  Biplane  with  160  h.p.  Mercedes  engine 

Halberstadt — 160  Mercedes 


It  was  reported  that  the  center  thrust  and  the  center 
of  resistance  of  the  plane  were  too  far  apart,  so  that  there 
was  a  tendency  to  stall  with  the  engine  on,  and  to  dive 
with  the  engine  off.  Directionally,  owing  to  propeller 
torque,  the  machine  would  swing  to  the  left,  but,  with 
engine  off,  would  be  neutral. 

Controllability  and  manceuverability  were  good. 

Details  of  Weight  and  Load  Carried 
Weight 

Average  total  weight  of  machine  fully  loaded   4,220  Ins. 

Load  Carried 

Pilot    18°  lhs- 

Observer    18°  lhs- 

Vickers  gun 

Lewis    gun    

Deadweight     


Standard 
Height 
10,000 
13,000 
15,000 
16,000 


Speed 
M.p.h. 
117.5 
113.5 
110.5 
108.5 


Speeds  at  Heights 

R.p.m. 
1,590 
1,565 
1,545 
1,530 


Speed 
M.p.h. 
120.5 
116.5 
114 
112 


R.p.m. 

1,725 
1,700 
1,675 
1,665 


16  Ibs. 
134  Ibs. 


Total  load   545  lbs- 

Carburetor,  Zenith,  2,004,  2,394;  jets,  289  main,  340  compensator. 

Climbs 

Result  of  Trials 

A.  B.  8,781  X.  3,012m. 

R.  of  C. 
ft./min.  R.p.m.  A.s.i. 

(1,540) 

1,040  1,620  71 
875  1,615  70 
600  1,605  69 
330  1,580  67 
275  1,575  66 


StandardTime 

H.ofC 

Time 

Height     Mins.     ft./min. 

R.p.m.  A. 

s.i.     Mins. 

0 

0 

(1,365) 

0 

2,000 

2.0 

935 

1,460 

71 

1.8 

5,000 

5.6 

770 

1,460 

70 

5.0 

10,000 

13.5 

500 

1,450 

69 

11.8 

15,000 

27.8 

230 

1,430 

67 

22.9 

16,000 

32.75 

180 

1,425 

66 

26.2 

Trials  at  4,500  ft.     Giving  Relation  between  Speed  and  Revolu- 
tions per  Minute  Flying  Level 


Flow 
Gals./Hr. 

25 

81% 

17 

14% 

12 
10% 
9 


The  installation  of  the  160  h.p.  Mercedes  is  on  the 
usual  German  lines  with  center  section  radiator,  main 
pressure  tank,  and  gravity  tank  in  top  center  section. 

The  wing  structure  is  a  single  bay  design  with  the  bay 
longer  than  usual  in  proportion  to  the  gap.  There  is  a 
small  anhedral  angle  on  the  top  planes,  and  dihedral  on 
the  bottom.  The  center  section  is  covered  top  and  bottom 
with  plywood. 

The  fuselage  is  three-ply,  covered  and  tapers  to  a  hori- 


Speed 

Flow 

Speed 

M.p.h. 

R.p.m. 

Gals./Hr. 

M.p.h. 

R.p.m. 

124 

1,600 

24 

127 

1,760 

120 

1,560 

21 

120 

1,685 

11C 

1,470 

17y4 

110 

1,575 

100 

1,375 

14'/2 

100 

1,470 

90 

1,280 

12y2 

90 

1,365 

80 

1,185 

10% 

80 

1,260 

70 

1,085 

»V4 

70 

1,150 

SINCLK   MOTOKK1)   AKUOl'l.AN  K.s 


209 


i-  nf  tin-  |MK!V  of  the  Hallterstiidt  two-seater  biplane,  160  h.p.  Mercedes  engine.     The  Inset  is  a  sketch  of  the  tall  plain-* 


zontnl  inrinlirr.  the  width  remaining  constant.  This  al- 
lows the  ri_-iil  fixing  for  the  tail  plane,  no  bracing  or 
struts  being  needed. 

The  tail  plane  is  adjustable  on  the  ground  only.  Tin- 
pilot's  and  gunner's  cockpit  are  constructed  as  one,  with- 
out apparently  weakening  the  fuselage. 

II  I'    at  revolutions  —  not  known. 

Propeller  —  Dia.  274  cm.     Pitch,  900  cm.  (marked). 

2,747  mm.  3,095  mm.   (measured). 

Military   load  —  545  Ib*. 
Total  weight,  fully  loaded  —  2,539  Ihs. 
W.-iirht  ,>,T  M).  ft.— 8.2  Ib*. 
\\ '.  ijrht  p«r  h.p.— 15.83  Ibs.  (h.p.  assumed  160). 


M.p.h.  H.p.m. 

S|«-cd  at  13,000  ft 8*  135J  approx. 

S|.«-<l  at  10,000  ft 97  1,'W5  approx. 


Mln.  Sec. 

Climb  to    5,000  ft 9  25 

Climl.  to  10,000  ft 24  30 

Climb  to  14,000  ft 51  55 


R.ofC.  in 
ft.  per  mln. 

240 

240 
80 


«4 

64 


Service  ceiling  (height  at  which  rate  of  climb  Is  100  ft.  per  mln.) 

—  13.500  ft. 

Kstinintrcl  nl.solute  cellln(r— 16,000  ft. 
Greatest  heiirfit  reached  —  14^00  ft.  in  64  min.  40  sees.     Rate  of 

climb  at  this  height  —  50  ft.  per  min. 


210 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Front  view  of  Pfiilz  single-seated  (ifrht- 
iii).'  plane,  equipped  with  1KO  h.p.  -Mer- 
ivdes  engine 


The  principal  dimensions  of  the  Pfalz  D.III.  are  as 
follows : 

Span  of  upper  wing  9M  metres. 

Span  of  lower  wing   7.80 

Total    length    7.06 

Height     -'.67 

Wings 

The  planes  are  unequal  in  span  and  chord,  and  stag- 
gered greatly  forward,  namely  0.43  metres.  The  planes 
are  not  swept-back.  The  lower  planes  have  a  slight  di- 
hedral angle.  The  trailing  edges  of  the  wings  are  rigid. 

The  upper  plane  is  trapezoidal  in  form,  with  rounded 
corners.  The  trailing  edge  is  cut  away  in  the  centre,  the 
recess  being  shallow  from  back  to  front  (0.225  metres) 
but  very  wide  (1.65  metres). 

At  the  ends  of  the  upper  plane  are  balanced  ailerons. 
The  plane  is  constructed  in  one  piece,  and  the  chord  is 
uniformly  1.65  metres.  Along  the  whole  length  are  12 
ribs  made  of  wood,  and  spaced  0.84  metres  from  one  an- 
other. The  incidence  of  the  seventh  rib  is  3%  degrees. 
Between  each  pair  of  ribs  are  three  strips  of  wood 
strengthening  the  leading  edge,  the  middle  of  these  runs 
back  to  the  rear  spar,  while  the  two  others,  which  are 
very  small,  stop  at  the  front  spar. 

The  two  main  spars  are  built  of  spruce.  They  are 
hollow  rectangular  boxes.  The  front  spar  is  0.20  metres 
from  the  leading  edge,  and  the  rear  spar  0.65  metres  from 
the  trailing  edge.  It  follows,  therefore,  that  the  distance 
between  the  axes  of  the  spars  is  0.80  metres.  The  posi- 
tion is  maintained  by  four  interposed  steel  tubes.  The 
structure  is  internally  braced  by  crossed  piano  wires. 

In  the  thickness  of  the  centre  section  of  the  wings  is 
found  a  petrol  tank  on  the  left,  and  the  radiator  on  the 
right.  This  section  is  heavily  reinforced  with  plywood. 

The  ailerons  are  balanced  and  upturned,  and  their  chord 
is  0.4  metres  at  the  h'-nge,  and  0.73  metres  at  the  broad- 
est part  of  the  balanced  portion.  They  are  2.265  metres 
long. 

Control  is  transmitted  from  the  control  pillar  to  the  lev- 
ers of  the  ailerons  by  3  mm.  cables  passing  through  the 
interior  of  the  lower  wings. 

The  lower  planes  are  trapezoidal  in  form,  as  are  the 
upper  planes,  and  the  ends  are  very  rounded  and  upturned. 
Their  chord  is  1.2  metres. 

At  a  point  0.2  metres  from  the  leading  edge  is  found 
the  front  main  spar,  the  rear  spar  is  0.5  metres  from  the 


The  Pfalz  Biplane  D.   III. 

trailing  edge,  and  the  distance  between  the  spars  from 
axis  to  axis  is  0.5  metres,  as  compared  with  that  of  0.8 
metres  in  the  upper  plane.  The  difference  in  this  dis- 
tance is  caused  by  the  difference  in  the  chords  of  the 
wings. 

On  each  wing  are  10  wooden  ribs,  spaced  0.35  metres 
apart.  At  the  seventh  rib,  that  is  to  say,  near  the  base  of 
the  interplane  strut,  the  incidence  is  3  deg. 

At  12  cm.  from  the  extremity  of  the  first  rib  on  the 
lower  left-hand  wing  is  a  strip  of  stamped  metal,  24  cm. 
wide,  resting  on  the  two  main  spars  and  forming  a  foot- 
board. 

The  system  of  false  ribs  and  compression  tubes  is  the 
same  as  that  in  the  upper  plane. 

The  lower  planes  are  attached  to  shoulders  constructed 
on  the  lower  walls  of  the  fuselage. 

The  gap  between  the  planes  is  1.415  metres  in  line  with 
the  fuselage,  and  1.375  metres  at  the  base  of  the  inter- 
plane  struts,  so  the  dihedral  is  not  very  apparent. 

The  cabane  slopes  outwards  and  upwards. 

The  struts  of  the  cabane,  and  those  between  the  planes, 
are  very  large  and  thick,  and  are  formed  of  streamline 
timber.  They  are  of  a  U-shape,  arranged  upside  down 
in  the  cabane  struts,  and  the  right  way  up  in  the  plane 
struts,  the  cross-pieces,  which  unite  the  legs  of  the  U  in 
the  cabane  struts,  being  found  above,  whereas  those  which 
unite  the  legs  of  the  interplane  struts  are  below. 

All  these  struts  are  fixed  with  the  aid  of  cup-joints, 
and  carry  sheet  metal  ferrules  at  their  four  poii.ts  of  at- 
tachment. 

Viewed  from  the  front  the  interplane  struts  are  in- 
clined outwards,  the  distance  between  the  tops  of  the  in- 
terplane struts  being  0.318  metres  greater  along  the  planes 
than  their  bases.  The  distance  between  their  front  and 
rear  branches  corresponds  to  the  distance  between  the 
main  spars  in  the  upper  plane,  to  which  they  are  attached. 
Their  attachment  to  the  lower  planes  is  different,  and  is 
made  to  the  piece  of  timber  which  unites  the  two  main 
spars. 

These  two  lower  points  of  attachment  are  0.3  metres 
apart  from  axis  to  axis. 

Bracing. —  The  plane-bracing  is  attached  to  the  sides 
of  the  fuselage. 

Two  4  mm.  cables  run  from  the  summit  of  the  cabane 
to  the  shoulders  on  the  lower  part  of  the  fuselage. 

Two  4  mm.  cables  run  from  the  top  and  bottom  re- 
spectively of  the  front  interplane  strut,  one  to  the  front 


SIXCI.K   MOTOHKl)  .\KH01M..\\KS 


111 


xirw    nf    tin-    I'fil/    -vi 
plane 


-eileil 


Iff  of  the  undcr-earriagc,  and   the  other   to  the  summit 

of  thr  front  cahanc  strut. 

'J'wn  ntlirr  t  nun.  cables  run  from  tin-  top  and  bottom 
rcsp! cthely  of  (In-  rear  intcrplanc  strut,  the  first  to  the 
front  of  thr  slioulilrr  of  tin-  I'IIM laire.  tin-  second  to  the 
.summit  of  the1  rear  cabane  strut.  These  cables  have  a 
inel  il  i-o -i-lion  it  their  intersection. 

A  Mi|i|ili  meut.-iry  i-ablr.  .:  nun.  ili.-imcter,  completes  the 
.structure  of  tin-  »iiii;s.  .-ind  roiinrrts  the  base  of  the  intcr- 
plane  struts  to  the  end  of  the  upper  plane.  Its  point  of 
att.-irhuii  nt  is  found  outside  these  struts,  0.81  metres 
from  tin  summit. 

All  thrse  eahles  are  connected  to  lugs  fixed  on  the  spars, 
and  ire  independent  of  the  interplanc  struts. 

The  Tail 

Tli>  ti\.  ,|  tail-plane  is  trapezoidal  with  a  rounded  Icad- 
:_'••  to  its  front  part.  Its  greatest  depth  is  0.88 
metres,  its  width  is  .'  l  :  m.tres.  A  permanent  portion 
of  plvui>«<j  is  limit  into  the  fuselage,  to  which  is  an- 
chored  the  fixed  tail-plane  proper.  The  assemblage  and 
fi\iiiLr  of  tin  se  sections  is  achieved  by  two  bands  of  metal 
placed  it  their  junction  aboM-  and  I.elou.  and  bolted  in 
pli<<  One  dm  s  not  remark  the  cable  found  in  the  first 
moil.ls  brought  down. 

Tlie  elevator,  which  is  unbalanced,  is  formed  of  a  sin- 
gle flap,  constructed  of  steel  tube  covered  with  fabric. 
Its  ilimeiisions  are  0.452  metres  chord  by  2.65  metres 
span. 

Tin-  rudder  is  balanced,  and  has  the  appearance  of  an 
oval  inclined  towards  the  rear.  It  is  situated  entirely 
;il.,,', ,  tin-  elevators.  Its  structure  is  metallic. 

Tin-  fixed  fin,  of  trapezoidal  shape,  is  formed  of  ply- 
wood, and  is  moulded  bodily  into  the  fuselage.  The  con- 
trols are  worked  by  3  mm.  cables,  which  pass  through  the 
interior  of  the  fuselage,  and  do  not  come  out  until  they 
arc  within  one  metre  of  its  rear  extremity. 

The  Fuselage 

fuselage  of  the  Pfalz  I). III.  is  of  monocoque  type, 
oval  in  section,  and  it  tapers  vertically  towards  the  tail. 
Its  seetion   is  very   large  at  the  portion   between   the 
lmt    \rry   narrow   in   front  and   towards   the   renr, 
presenting  a  remarkable  likeness  to  a  torpedo. 

It  is  entirely  constructed  of  bands  of  plywood,  9  em. 
wide,  and  it  terminates  on  the  upper  side  with  •  ridge. 


It  is  apparently  constructed  in  two  halves  on  moulds  (like 
the  early  Deperdussins  of  Mr.  Koolhov.  us  design),  after 
which  the  whole  structure  is  covered  with  thin  fabric  and 
painted. 

Inside  the  fuselage  are  found  eight  very  thin  cross  par- 
titions, which  divide  up  its  whole  length.  There  are  also 
eight  small  longerons;  one  in  the  ridge  along  the  back, 
(lire,-  on  cither  side,  and  one  at  the  \> 

The  section  at  the  centre  of  gravity  is  0.865  x  1.16  m. 
taken  at  the  axis  of  the  lower  plane. 

Controls 

The  control  of  the  machine  is  effected  with  the  aid  of 
a  control  column  with  a  handle  formed  of  two  branches 
sloping  towards  the  pilot.  The  hand-grips  are  bound 
with  cord.  In  the  centre  are  two  buttons  which  work 
the  machine-guns.  Thr  control  column  can  be  fixed  when 
climbing  or  diving  by  n  little  toothed  wheel. 

The  rudder  bar  is  adjustable  and  the  seat  is  fixed. 

Tin-  starting  magneto  is  found  on  the  left-hand  side 
in  front  of  the  pilot. 

Level  with  the  pilot  under  the  fuselage  are  two  holes 
with  plugs,  to  permit  the  draining  off  of  oil.  petrol,  or 
water,  which  might  damage  the  plywood  if  allowed  to 
collect. 

.lust  in  front  of  the  tail-plane  there  is  found,  on  either 
side  of  the  fuselage,  an  opening  large  enough  for  the 
passage  of  the  hand.  This  gives  a  better  grip  when  lift- 
ing the  machine  than  would  the  bare  fuselage. 

The  tail-skid  of  special  section  is  constructed  of  ash, 
and  is  reinforced  by  metal  where  it  touches  the  ground. 
The  springing  of  the  tail-skid  is  effected  by  elastic  cord. 

The  airscrew  in  common  use  is  an  "  Axial  "  2.82  metres 
in  diameter,  placed  underneath  a  revolving  pot,  or  "  cas- 
serole." On  certain  other  Pfalz  aeroplanes  has  been 
found  the  "  Heine  "  airscrew,  2.78  metres  in  diameter,  or 
yet  again  the  "  Imperial  "  airscrew  2.70  metres  diam<  ••  r 

The  Engine 

The  engine  is  a  modified  I60-!i.p.  Mercedes,  c<|iiippcd 
with  double  ignition,  and  a  horizontal  exhaust  pi|>c  on 
the  right-hand  side.  The  form  of  the  exhaust  pipe  \  m-  s 
In  certain  types  it  is  a  cornucopia,  and  the  emission  nf 
gas  l»  made  in  front  of  the  first  cylinder.  On  other  ma- 
chines the  end  of  the  exhaust  pipe  is  taken  in  the  reverse 
direction,  the  exhaust  being  emitted,  instead,  at  the  rear 
of  the  last  cylinder. 


212 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  engine  cowl  leaves  the  upper  part  of  the  cylinders 
uncovered. 

The  petrol  supply  is  provided  by  a  main  tank  of  about 
70  litres  capacity,  placed  in  front  of  the  pilot  on  the  floor 
of  the  machine,  and  by  a  tank  built  into  the  upper  plane 
with  a  capacity  of  -10  litres.  In  all,  110  litres  of  petrol 
are  carried  and  15  litres  of  oil. 

The  radiator  is  of  the  system  of  layers  frequently  em- 
ployed in  chasing  machines.  It  contains  40  litres  of  wa- 
ter. On  its  lower  face  is  found  a  large  aluminium  plate 
fixed  in  two  grooves,  which  makes  it  possible  for  the  pilot 
to  cover  or  uncover  the  radiating  surface. 

Armament. —  This  consists  of  two  fixed  Spandau  ma- 
chine-guns operated  by  the  engine,  and  firing  through  the 
airscrew.  They  are  arranged  one  on  each  side,  a  little 
above  the  cylinders,  and  can  be  fired  separately  or  to- 
gether. 

The    Landing    Carriage.— This    is     formed    by    four 


streamline  steel  tubes  50  by  30  mm.,  which  constitute  two 
"Vs." 

The  two  front  legs  are  joined  by  an  arched  strip  of 
metal  which  supports  the  front  portion  of  the  fuselage. 
A  lug  embodied  in  the  upper  extremity  of  eacli  strut  forms 
the  attachment  of  a  cable  running  to  the  front  interplane 
strut. 

The  steel  axle,  53  mm.  diameter,  is  placed  between  two 
wooden  pieces.  A  movable  and  hinged  plate  covers  the 
whole  arrangement,  and  acts  as  a  streamline  fairing.  The 
suspension  is  rendered  elastic  with  the  aid  of  metal  springs 
covered  with  fabric,  arranged  like  rubber  cord. 

A  metal  cable  limits  the  travel  of  the  axle. 

The  track  of  the  wheels  is  1.72  metres.  The  wheels 
are  fitted  with  760  by  100  mm.  tires. 

Below  is  given  a  summary  of  results  on  tests  of  several 
German  aeroplanes : 


View  from  above  of  the  German  Pfalz  single-seater  fighter,  showing  rudder  construction. 


SINC.I.K   MOTOKK1)  A  KHO1M  ,.\  \  |  g 


Vr- 


'214 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 
Pfalz  Scout  828  4  17— 160  Mercedes 


The  performance  of  this  machine  appears  to  be  prac- 
tically the  same  as  that  of  G/141   Pfalz  Scout  with  160 
h.p.  Mercedes,  tested  in  March,  1918. 
Summary  of  Results 


•gib 

u 

Q 

d  .5 

5 

._: 

1.5 

0  = 
o< 

5 
p. 

1 

£  jj« 

BS  4) 

d 

«j 

H  ^ 

PS  ^ 

pa 

< 

0 

(1,335) 

(1,320) 

5,000 

7.0 

606 

1,370 

67 

6.9 

605 

1,330 

73 

10,000 

17.3 

373 

1,350 

61 

17.5 

360 

1,310 

57 

14,000       32.3 

187 

1,320 

54 

33.7 

160 

1,290 

61 

Standard 
Height 
10,000 

Speed 
M.p.h. 
98.0 

R.p.m. 
1,415 

Speed 
M.p.h. 
102.5 

R.p.m. 

1,400 

13,000 

94.8 

1,395 

96.0 

1,355 

Details  of  Weight  and  Load  Carried 

8,284/17  G/141 

Military   Load    3»l  "».  281  Ibs. 

Total  Weight,  fully  loaded    2,085  Ibs.  2,056  Ibs. 

On  this  machine  lift  wires  have  been  added  to  the  over- 
hang, running  from  bottom  rear  main  plane  fitting  to 
about  half  way  along  the  back  spar  overhang. 

Front  openings  have  been  cut  in  the  engine  cowling  to 
the  cylinders,  the  former  Pfalz  being  left  plain. 

The  tail  plane  has  been  increased  from  12.1  sq.  ft.  to 
16.2  sq.  ft.,  but  the  shape  has  been  altered,  being  now 
nearly  semi-circular. 

Main  plane  incidence  and  tail  plane  setting  are  approxi- 
mately the  same. 


Trials  on  Aviatik  No.  G.H.Q./4 


Duty  —  Reconnaissance. 

Engine  —  Benz.     Assumed  200  h.p. 

Propeller  — Wotan.     Dia.— 3,004.     Pitch  — 1,650    (measured). 

Military  load  — 545  Ibs. 

Total  weight  fully  loaded  — 3,325  Ibs. 

Weight  per  sq.  ft.—  7.46  Ibs. 

Weight  per  h.p.—  16.62  Ibs. 

M.p.h.  Revs. 

Speed  at  10,000  ft 9?i/2  MOO 

Speed  at  15,000  ft 89'/2  1,510 


R.ofC. 

Indicated 

Min.  Sec. 

ft./min. 

Air  Speed 

Revs. 

19      45 

345 

63 

1,490 

40       15 

165 

58 

1,470 

Climb  to  10,000  ft.... 
Climb  to  15,000  ft.... 
Service  ceiling  (height  at  which  rate  of  climb  is  100  ft.  per  mm.) 

— 16,750  ft. 

Estimated  absolute  ceiling— 19,500  ft. 
Greatest  height  reached  —  1 7,000  ft.,  in  5(i  min.  20  sec. 
Rate  of  climb  at  this  height  — 90  ft.  per  min. 


Dimensions  and  Equipment  of  the  1918-1919  Types  of  German  Aeroplanes 

The  following  table  permits  readers  to  compare  the  points  of  the  fighting  German  aeroplanes : 


Machine 


Type 


Albatros     D.  II 

Albatros     D.  Ill 

Torpedo    D 

Roland    D-  II 

Halberstadt     D 

Fokker    

Rex    D-  II 

Roland    C 

A.  E.  G C.  IV 

L.  V.  G C.  IV 

D.  F.  W.  Aviatik C.  V 

Albatros  B.  F.  W.   . . . C.  V 

Rumpler     

Gotha    G.  I. 

A.  E.  G 


'     r 
'•  1i 

5* 

Span 
Upper      Lower 

ft.    in.       ft.    in. 

07    s        OR    1 

Gap 

ft.    in. 
4     ® 

Chord 

ft.   in. 
5     3 

Length 
Over  All                    Motor 

ft.    in. 

24      O     MprppHps     

"3 

1! 

175 

•s  . 

0     E 

2 

6 
£  C 
0 

"9 

g 

28 

g 

4 

10 

4  10 

24 

0 

Mercedes    

175 

2 

0 

Mercedes    

175 

2 

0 

29 

g 

28 

o 

4 

4 

4     9 

22 

fi 

175 

2 

0 

28 

6 

25 

9 

4 

3 

4  10 

24 

0 

Mercedes  or  Argus  .  .  . 

120 

2 

0 

29 

6 

20 

6 

4 

3 

4  10 

24 

0 

Mercedes  or  Oberursel 

175 

9 

0 

33 

0 

33 

0 

4 

o 

5     3 

175 

1 

a 

42 

g 

41 

0 

g 

a 

5     5 

23 

g 

175 

2 

4 

n 

44 

g 

6     5 

28 

0 

235 

2 

4 

-i 

43 

g 

42 

o 

5 

g 

5     9 

228 

2 

6 

a 

41 

3 

40 

o 

5 

10 

5  10 

28 

o 

225 

a 

4 

a 

Mercedes    

260 

2 

6 

g 

78 

0 

79 

0 

7 

a 

7     g 

41 

o 

520 

3 

14 

3 

Two  Benz    .           

450 

2 

.. 

•  '•'•' 

A  tf 

(/  \  I/ 


GERMAN  'TYPE.   C  IV 

&UMPLEQ 

Z60    HP     I9IT     MPLANE 


Jcale  of    feet 

I^^^T"~I  M  •  I  »  T  I  T  T  I 

•*>«»«    i   «    *    'Q  " 


Mclaughlin 


215 


216 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  German  Rumpler  Biplane 

The  C.   IV  Rumpler  Biplane 


The  Rumpler  biplane  described  below  is  a  general  util- 
ity machine,  and  is  perhaps  the  best  in  its  class.  It  is 
chiefly  of  interest  on  account  of  its  great  speed,  which  is 
equal  to  that  of  a  chaser  single-seater,  and  also  on  ac- 
count of  its  high  "ceiling"  (6.500  metres).  The  climb 
of  the  Rumpler  C.IV  is  also  very  good  (5000  metres  in 
35  minutes). 

General  Specifications 

Span,  upper  plane    12.60        Metres 

Span,  lower  plane   12.10     .   Metres 

Chord,  upper  plane  1.70        Metres 

Chord,  lower  plane   1.30        Metres 

Area,  upper  plane  20      Sq.  Metres 

Area,  lower  plane   13.50  Sq.  Metres 

Gap  between  planes   1.85        Metres 

Stagger    0.60        Metres 

Overall    length 8.40        Metres 

Overall    height    3.25        Metres 

Engine,    Mercedes    260        h.p. 

or   Mayhach    250         h.p. 

Climb  in  35  minutes  5,000        Metres 

Wings 

Both  upper  and  lower  wings  are  swept  back  3  degrees. 
There  is  a  dihedral  angle  of  2  degrees  and  the  wings  are 
staggered  forward  0.60  metres.  The  trailing  edge,  con- 
trary to  usual  German  practice,  is  rigid.  The  ribs,  which 
are  made  of  three-ply  wood,  pierced  for  lightness,  are 
spaced  0.30  metres  apart.  Their  angle  of  incidence  is 
uniform  and  is  equal  to  5  degrees. 

In  the  plan  the  upper  wings  are  of  trapezoidal  form, 
with  rounded  angles.  Above  the  fuselage  the  trailing  edge 
is  cut  out  as  shown  in  the  illustrations.  The  maximum 
chord  is  1.70  m.  In  each  of  the  upper  wings  there  are 
19  main  ribs,  and  five  compression  struts  of  steel  tubes. 
The  ailerons  are  of  the  tapering  type,  their  chord  vary- 
ing from  0.50  to  0.65  m.  The  lower  wings,  as  in  so  many 
other  German  machines,  have  rounded  wing  tips.  As  the 
radius  of  the  arc  forming  the  rear  edge  is  longer  than 
that  of  the  front,  the  wing  tip  somewhat  resembles  that 


of  a  propeller  blade.      Each  of  the   lower  wings  has   17 
main  ribs,  and  four  steel  tube  compression  struts. 

The  interplane  struts,  of  which  there  are  two  pairs  on 
each  side  of  the  fuselage,  are  oblique.  In  section,  the 
inner  front  struts  measure  0.105  m.,  and  the  rear  strut 
0.130  m.,  while  the  outer  front  strut  measures  0.090  m. 
and  the  rear  outer  strut  0.085  m.  The  gap  between  the 
wings  is  1.85  m.,  and  the  total  lifting  surface  is  .S3. 5 
square  metres,  of  which  the  upper  wing  is  20  square  me- 
tres and  the  lower  wing  13.5. 

Tail 

The  tail  plane,  which  is  not  adjustable,  is  not  so  deep 
as  in  previous  types.  In  plan,  the  leading  edge  of  the 
tail  plane  is  approximately  a  semi-circle.  This  tail  plane 
is  supported  on  each  side  by  struts  attached  at  their  other 
end  to  the  bottom  rail  of  the  fuselage.  Two  other  struts 
brace  the  tail  plane  to  the  vertical  fin.  The  struts  under 
the  tail  plane  are  provided  with  a  series  of  sharp-edged 
metal  points.  It  appears  probable  that  the  object  of 
these  is  to  prevent  the  landing  crew,  when  wheeling  the 
machine  about,  from  catching  hold  of  these  struts,  thus 
possibly  bending  them.  The  elevator  is  in  two  parts,  each 
of  which  is  partly  balanced  by  a  triangular  forward  pro- 
jection. The  rudder,  which  is  built  up  of  metal  tubes,  is 
of  the  usual  type,  and  the  control  cables  pass  inside  the 
fuselage,  guided  at  points  through  small  wooden  tubes. 

Fuselage 

The  construction  of  the  fuselage  is  of  the  current  type, 
with  four  longerons  and  struts  and  cross  members,  braced 
by  piano  wire.  Front  and  rear  are  covered  with  three- 
ply  wood,  and  the  middle  with  fabric.  The  propeller  (ai 
Heine)  has  a  diameter  of  3.17  m.  As  on  all  other  Ger- 
man machines,  the  propeller  boss  is  enclosed  in  a  "  spin- 
ner." 

Engine 

The  motor  fitted  on  the  Rumpler  is  either  a  260  h.p. 


SINC;i.K   MOTOKK1)  A  KK(  >1'1 .  \  \  I  - 


-.'IT 


\    liMMipl.-r  type  of  German  machine.     Vote  the  lo.v.ti,.i.  ..f  the  radiators 


Mcrrr.lrs   or   a    -'.-><>   h.p.    Maybach.   both   having  six   v.  r 
tical  cylinders. 

When  Hi.  Mere,-,!.-,  i,  titt.-d,  it  is  slightly  tilted  to  the 
right,  in  order  to  allow  thr  induction  pipes  to  pass  between 
tin-  legs  of  thr  cabanr.  With  tin-  May  bach,  which  offers 
less  riiriinihr.-inrr.  this  arrangement  is  not  necessary.  The 
motor  is  supplied  with  furl  fnnn  two  tanks.  The  main 
,,n,  (about  -."Jd  litrrs)  is  placed  under  tlir  scat  of  tin- 
pilot,  thr  second,  the  serviee  tank  (about  70  litres),  is 
pla, -,,!  ,t  the  back  of  thr  pilot  between  him  and  the  gun 
rim:  in  thr  Dinner's  ,-oekpit.  The  quantity  of  fuel  car- 
rird  allows  of  a  flight  of  four  hours'  duration.  The  eov- 
ering  over  Hi.  mgine  leaves  the  top  of  the  cylinders  ex- 
posed,  .-.n.l  encloses  a  Spandau  machine  gun  operated  by 
tin-  motor. 

The  exhaust  pipes  run  from  the  six  cylinders  to  a  cor 
mon    chimney,    eurving    upwards    and    backwards.     The 
cliiiiinev   itself   is   ,li»ided.  about  half  way  up,  into  three 
l.ranehrs.   probably   in   order   to   obtain  a  certain  amount 


of  silencing  effect.  As  in  previous  mod.  Is.  the  radiator, 
which  is  semi-circular  in  shape,  is  placed  on  thr  front 
,-f  the  eahane.  In  front  of  it  is  a  series  of  small 
slats,  whirh  can  hr  moved  so  as  to  be  either  parallel  to 
or  at  right  angles  to  the  direction  of  flight.  This  is,  of 
course,  don,  in  order  to  make  it  possible  for  the  pilot  to 
adjust  the  cooling  according  to  the  altitude  at  which  he 

is  Hying. 

Behind  the  motor  is  the  pilot's  cockpit,  and  behind 
again  that  of  the  gunner.  Supported  on  a  gun  ring  in  the 
rear  cockpit  is  a  Parabellum  machine-gun.  Pilot  and  gun- 
ner are  very  close  together.  In  the  gunner's  cockpit  there 
is  a  bomb  rack  of  the  usual  type,  carrying  four  bombs. 
An  opening  in  the  floor  permits  of  taking  photographs, 
and  the  machine  carries  a  wireless  set.  Thr  landing 
chassis  is  of  the  V  type,  with  rubber  shock  absorber.. 
There  is  no  brake  fitted  on  this  machine.  An  external 
drift  cahlr  runs  from  the  nose  of  the  fuselage  to  the  foot 
of  thr  inner  front  interplane  strut. 


rrman   Rumpler  type  machine 


CURTI5S— 18-1 

400  HP  'K-12   ENGINE 

TRIPLANE 


Scale  of   Peet 


McUugtilij 


218 


SIM.I.K    MOTOKK1)  A  KHO1M  ,.\  \  I  - 


The  Curtiss 
Model  18-T  Triplane 


This  machine  was  designed  for  speed  and  great  climb- 
ing ability. 

General  Dimensions 

Wing  Span— I'pper  Plane 31   ft.  11  in. 

Wing  Span  —  .Middle   Plane   31   ft.  n  in. 

Wing    Span  —  Lower    Plane    31    ft.   \\   fa 

Depth  of  Wing  ford  (I'pper,  Middle  and  Lower)    44  in. 
Gap      iM-tween       Wing-      (In-twccn      I'pper      and 

Middle)    43  in. 

Cap     iMtweeii     Wing-     (between     Middle     and 

Lower)     3*^«  in. 

••r    None 

Length  of  Machine  overall 93  ft.  3^8  in. 

Height   of  Machine  overall   9  ft  10%  in. 

Angle  of  Incidence  gyt  degrees 

Dihedral     \ngle    None 

;>l>ack    5  degrees 

Wing   Curve    Slonnc 

'iilal  Stabiliser  —  Angle  of  Incidence 0.5  degrees 

Areas 

Wings-- I'ppcr     .' 119.0   sq.    ft. 

Wing--     Middle     87.71    sq.    ft. 

Wing-       Lower      87.71    sq.    ft. 

-on-  (Middle  10.79;  Lower  10.79)   SIM   sq.    ft. 

llori/.ontal   Slahilicer 14.3    sq.    ft 

Vertical    Stiibiliser    5.;.'    sq.    ft. 

..rs  (each  6.51 )    13.09  sq.   ft 

Hiiddcr     8.66    sq.    ft. 

Total   supporting  surface   309.0  sq.   ft. 

Loading   (weight  carried  per  sq.  ft.  of  support-  9.4  Ibs. 

ing  surface)    

Loading  (per  r.h.p.)    7.35   Ibs. 

Weights 

Weight  —  Machine   Empty   1,895  Ihs. 

u  eight  —  Machine  and  Load   9,901  Ibs. 

f-efiil  I  ..ad  1.076  Ibs. 


Fuel     400  Ib*. 

Oil     , 45  Ibg. 

Pilot  and   Pits.eiurer   S30  Ibs. 

Useful  load   au\  |bs. 


Total     1.076  Ibs. 

Performance 

Speed  —  Maximum  —  Horisontal  Flight  163  m.p.h. 
Speed  — Minimum— Horisontal  Flight  58  m.pji. 
Climbing  Speed  15,000  ft.  in  10  minute* 

Motor 
Model    K-1J—18-C) Under,    Vee  —  Four-Stroke    Cycle.    Water 

cooled. 

Horse  Power    —(Rated)  at  9,500  r.p.m.   400 

Weight  per  rated  Horse  Power   I  To 

Bore  and  Stroke   4%  x  8 

Fuel  Consumption  per  hour  36.7  gals. 

I  in  I  Tank  Capacity   67  gaU. 

( >il  Capacity   Provided  —  Crankca-c   6  gauu 

Fuel    Consumption    per    Brake    Horse    Power    per  .55  Ibs. 

hour      030  Ibs. 

Oil  Consumption  per  Brake  Horse  Power  per  hour  Wood 
Material    Cl.ick«itc 

Propeller 

Pitch  —  according  to  requirements  of  performance. 
Diameter  —  according  to  requirements  of  performance. 
Direction  of  notation  (viewed  from  pilot's  seat)... 

Details 

One  pressure  and  one  gravity  gasoline  tank  located  In  fuselage. 
Tail  skid  independent  of  tail  post;  Landing  gear  wheel,  sixe  X 
In.  x  *  in. 


Maximum  Range 
At  economical  speed,  about  55O  mile-. 


Three-quarter  rear  rtew  of  the  Curtiss  Model  18-T  Triplane  with  a  400  Kp.  Curtiss  Model  K  engine 


220 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


SINC1.K    MOTOKK1)  AKKOIM.A  NKS 


•-'•_'  I 


ThriT  ijiiarlrr  re.-ir  \  lew  nf  the  Sopwilh 
TripL-inc.  Vote  tin-  single  struts  and  the 
uilrnms  mi  nil  Hirer  »  .: 


The  Sopwith  Triplane 


What  prnli.ilily  has  led  to  the  return  of  the  triplane 
form  of  construction  is  tin-  small  span  which  it  en- 
.•ililt  s  »n,  to  use.  Another  advantage  of  the  triplane 
arraiigi  nn nt  is  that  tlif  aspect  r.-itio,  which  .should  not  he 
less  tli.-in  il.  hut  which  in  many  machines  of  sii.irt  span 
often  has  to  It-  considerably  less,  can  be  more  easily  ar- 
ranged for  in  the  triplane.  Thus  in  the  case  of  the  Sop- 
with triplane  the  chord  is  only  little  over  1  metre,  and 
the  span  is  8  metres.  The  increased  wing  resistance  is 
counteracted  by  the  employment  of  only  one  strut  on  each 
.side  anil  a  very  simple  wing  bracing.  Furthermore  it  is 
possible,  owing  to  the  light  loading  of  the  wing*,  to  con- 
struct the  wing  spars  considerably  lighter,  and  still  have 
a  comparatively  great  free  length  of  spar,  in  the  case  of 
~  MM  ith  triplnnes  about  2.75  m.  with  an  overhang  of 
l.Ni  in.  Tin-  weight  of  the  total  wing  area  will  there- 
fore sc.-ircely  come  out  greater  than  in  the  case  of  a  bi- 
plane of  the  same  area.  Possibly  also  the  arrangement 
of  the  wings  is  advantageous  as  regards  the  view  obtained 
by  tli>-  pilot,  as  the  middle  wing  is  about  on  a  level  with 
nd  the  upper  and  lower  wings,  on  account  of 
tin  ir  small  chord,  do  not  obstruct  the  view  to  as  great 
an  extent  as  the  wings  of  the  ordinary  smaller  biplane 
liavini:  i  greater  wing  chord.  While  both  lift  wires  pass 
in  front  of  the  middle  wing,  the  landing  wire  runs  through 
it.  The  bracing  cables  for  the  body  struts  are  crossed 
in  the  ease  of  those  running  forward  to  the  nose  of  the 
machine,  while  those  bracing  the  struts  in  a  rearward 
•>n  are  straight.  The  gap  between  the  wings  is 
!>n  centimetres,  and  the  stagger  is  about  25  per  cent.  All 
ngs  are  fitted  with  wing  flaps  connected  by  a  ver- 
•ei-1  band.  In  the  nose  the  body  carries  a  110  h.p. 
t  rotary  motor,  enclosed  in  a  circular  cowl,  which 
•s  below  the  body  in  order  to  allow  the  air  to  escape. 
Tin-  body  is  of  rectangular  section,  rounded  off  in  front 
by  M»  ans  of  a  light  wooden  framework  in  order  to  make 
it  merge  into  the  curve  of  the  engine  cowl.  The  width 
of  the  fuselage  is  0.70  m.,  and  it  tapers  to  a  vertical  knife- 
edge  at  the  back,  to  which  the  rudder  is  hinged.  The 
elevator  is  in  two  parts,  and  has  in  front  of  it  a  tail  plane 
of  about  3  metre  span,  which,  as  in  all  Sopwith  machines, 
can  have  its  angle  of  incidence  adjusted  during  flight. 

The  area  of  the  Sopwith  triplane  is  27  square  metres, 
so  that  for  a  total  weight  of  670  kilogs.  the  wing  loading 


is  only  2.r>  kilogs.  per  square  metre.  With  such  a  light 
loading  the  machine  has  undoubtedly  a  considerable  speed 
and  a  very  good  climb.  Further  particulars  relating  to 
these  have  not  yet  U -en  published  up  to  the  present.  The 
triplane  is  built  both  as  a  single-seater  and  as  a  two- 
seater,  and  has  always  a  fixed  machine-gun  in  front  above 
the  fuselage,  and  in  the  ease  of  the  two-seater  another 
machine-gun  operated  by  the  observer.  This  increase* 
the  weight  of  the  two-seater  by  about  KM)  kilogs. 

The  under-carriagr  consists,  as  in  all  Sopwith  machines, 
of  two  V's  of  steel  tubing  and  a  divided  wheel  axle.  Un- 
hinge of  which  is  braced  from  the  fuselage. 

The  following  remarks  are  taken  from  a  technical  re- 
port: 

The  fuselage  with  tail  plane  and  rudder  is  the  same  as 
that  of  the  small  Sopwith  single-seater  biplanes.  The 
three  wings  have  a  span  of  8.07  m.  and  a  chord  of  1  m. 
The  lower  and  middle  wings  are  attached  to  short  wing 
sections  on  the  fuselage.  The  upper  plane  is  mounted  on 
a  small  center  section  supported  by  struts  from  tin-  body. 
Both  spars  of  the  upper  wing  are  left  solid,  while  those 
of  the  lower  and  middle  are  of  I-section.  The  interplane 
struts,  which  are  of  spruce,  and  of  streamline  section. 
run  from  the  upper  to  the  lower  wing,  and  the  inner  ones 
from  the  upper  wing  to  the  bottom  rail  of  the  fuselage. 
In  order  to  give  a  better  view  the  middle  wing,  which  is 
on  a  level  with  the  pilot's  eyes,  in  cut  away  near  the  fuse- 
lage. 

The  wing  bracing  is  in  the  form  of  streamline  wires 
of  '/4"'n-  diameter.  The  very  simply  arranged  landing 
wires  are  in  the  plane  of  the  struts,  while  the  bracing  of 
the  body  struts,  as  well  as  the  duplicate  lift  wires,  are 
taken  further  forward.  From  the  rear  spar  of  the  mid- 
dle wing,  wires  are  run  forward  and  rearward  to  the  up- 
per rail  of  the  fuselage,  and  the  lower  wing  also  has  a 
wire  running  forward  to  the  lower  rail  of  the  body.  All 
the  planes  have  wing  flaps,  and  inspection  windows  of 
celluloid  are  fitted  over  the  pulleys  for  the  wing  flap 
cables. 

The  motor  is  a  110  h.p.  Clerget,  and  the  petrol  is  led 
to  the  engine  by  means  of  a  small  propeller  air  pump 
mounted  on  the  right  hand  lody  strut.  As  the  air  screw 
was  not  in  place  we  cannot  give  details  of  it.  In  tin- 
pilot's  seat  were  the  following  instruments:  On  the  right 


222 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


A   British  pilot  preparing  for  a  flight  in  a  Clerget-motored 
Sopwith    triplane 

hand  wheel  for  varying  the  angle  of  incidence  of  the  tail 
planes,  a  hand  operated  air  pump  and  a  petrol  indicator. 
In  the  middle,  air  speed  indicator,  manometer,  clock,  revs, 
indicator,  and  switch.  On  the  left  a  petrol  tap,  lever  for 


regulating  the  air,  and  lever  for  regulating  the  petrol. 
The  weight  of  the  machine  empty  was  found  to  be  490 
kilogs.,  and  if  the  useful  load  is  assumed  to  be  200  kilogs., 
we  obtain  a  total  weight  of  690  kilogs.,  which,  with  an 
area  of  21.96  sq.  metres,  would  give  a  loading  of  31.4 
kilogs.  per  square  metre. 

Further,  the  following  particulars  are  given:  Motor: 
Clerget,  nominal  h.p.  110,  brake  h.p.  118;  fuel  capacity 
for  two  hours,  petrol  85  litres,  oil  23  litres;  area  of  wings 
and  flaps  (square  metres),  upper  7.90,  middle  6.96,  lower 
7.10,  total  21.96;  area  of  elevators  6  by  .5,  of  wing  flaps 
1.10,  of  rudder  .41.  Angle  of  incidence  (degrees)  :  upper 
wing,  root  -(-I,  tip  — .8;  middle  root  -f-  1.5,  tip  -)-  1.5; 
lower,  root  -)-.5,  tip  — .5 ;  tail  plane,  variable  -{-  2  to 
—  2  degrees.  Loading  per  sq.  metre,  empty  22.3,  fully 
loaded  31.4;  loading  per  brake  h.p.  empty  4.15,  fully 
loaded  5.85. 


At  economic  speed,  about  550  miles. 


Fuselage  with  under-carriage  and  accessories .... 

Wings -. 

Tail  plane,  rudder  and  elevator  

Engine    

Petrol    tank    

Oil   tank 

Propeller     

Engine  accessories    

Mounting     


Total  weight  empty  

Pilot    

Gun  and  ammunition  

85  litres  of  petrol  and  23  litres  of  oil 


Weights 
in  kilograms 
133.5 
135 
13 
160 
15 
8.5 
10 
16 
3 


Total  weight,  useful  load 


490 
80 
40 
80 

-'00 


Interior  of  the  Sopwith  factory,  showing  one  of  the  triplanes  being  assembled,  and  in  the  background   the  biplanes 


MULTI-MOTORED  AKKoi'l.AM.s 


228 


The  remarkable  "  baby  "  Caoroni  triplane  scout,  the  smallest  member  of  the  Caproni  family,  Mr.  Capronl  standing  by 


Sim-,-  UK-  War,  both  the  Cnpronl  biplane  and  trlplanr  have  been   remodelled    for  paswnp-r   travel   or  rommerrial   purposes. 
__  !.,,,!  ,,,.    I,...,  lH-,-n  litti-d  with  H  rabin  to  accommodate  eight  JMTV.M-:  outside  there  arc  seat*  for  the  two  pilots  and  for  nn..tbrr 
rnn-hnnic;  iimlrr  thr  p.isM-nger  seat*  then-  U  riM.in    for  J>*>  ll>v  of  mail.     Thr  hiplalir  roinnnlly  ,.,rri.-.  p.t~,,\,  -nr   for 
1  1..-  triplane.  equip|«-d  with  three  Liberty  engines,  has   been   fitted   with   a   passenger   rabln.   with   acrommodiition    for 


inside  and  four  others  alwve. 


•J-24  TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 

Perspective  Sketches  of  the  German  Fokker  Triplane 


The  upper  sketch  shows  a  three-quarter  rear  view  of  the  Fokker  Triplane.    This  illustration  gives  a  good  idea  of  the  gene 
arrangement  of  this  interesting  machine.     Xote  the  small  veneer  plane   enclosing   the   wheel   axle.     Below   is    a   three-quarter   frtl 
view  of  the  Fokker  Triplane.     The  thickness  of  the  wings  can  be  imagined   from   an   inspection   of  this  drawing.     The  pin-jointl 
struts  are  really  ties  rather  than  struts  as  they  are  working  in  tension 


SI.\(.I.K   MOTOKKI)  AKUOIM.AM  9 
The  Fokker  Triplane 


The    Fokkcr   triplane   can   IK-  said   to  be  of   the   "  wire- 
•ss  "  type. 

The  internal  construction  of  th.  wings  i^  .Jesigi,. 
ro\  iile  nil  the  strength  without  anv  external  aid  of  anv 
tind.  The  interplane  struts,  which  are  really  ties  rather 
bin  struts,  might  conceivably  have  been  omitted  alto 
rcthcr,  and  so  tar  as  om  is  able  to  judge,  their  onl\  func- 
ion  is  to  help  to  distribute  the  load  more  evenly  b.  tw.in 
he  three  wings.  It  is  well  known  that  in  a  biplane  the 
ipp.r  wing  carries  about  four-sevenths  of  tin  total  load 
when  the  wings  are  of  equal  section,  span,  and  chord  > 
nd  the  lower  wing  about  three  scv  enths.  In  a  triplane 
tiucli  the  sum  distribution  is  found,  with  the  exception 
hat  the  middle  and  lower  wing  each  take  a  share  (not 
(|iial  '  of  the  three  sevenths  of  the  total  load. 

Ill  the  Fokkcr  triplane  the  upper  wing  is  of  larger  span 
han  the  middle  wing,  which  in  turn  is  of  slightly  greater 
pan  than  the  low.  r  wing.  In  consequence,  as  the  three 
iing~  appear  to  In-  all  of  the  same  section,  the  upper  wing 
itist  carry  more  than  four  sevenths  ot  the  total  load.  In 
rder  to  provide  a  licttcr  load  distribution,  the  middle  and 
IIW.T  wings  are  made  to  carry  their  share  of  the  load 
n  the  top  plane  by  connecting  them  to  this  ria  thin  high 
nen.  ss  ratio  struts,  which  are  in  reality  ties  as  they 
re  working  in  ten*  MI  This  explains  why  the  struts 
re  so  ex)  ninety  thiii  (about  '  ._.  in.)  and  the  moment  of 
nertia  of  the  strut  section  would  be  so  small  that  the 
truts  would  buckle  under  a  very  small  load  if  subject  to 
(impression 

The  fact  that  no  lift  bracing  is  employed  naturally 
wing  spars  of  considerable  depth  if  the  spar 
rcight  is  to  U'  kept  reasonably  low.  and  in  the  Fokkcr 
riplane  this  has  been  attained  by  making  the  wing  sec- 
ion  very  thick  in  proportion  to  the  chord.  Roughly,  the 
i.ixiiiiiiin  c  tmh.  r  is  in  the  neighborhood  of  one-eighth  of 

•T<1. 

•wo  wing  spars  are  placed  very  close  together,  and 

ios.  d   in  a  box  of  three-ply  wood.     The   function 

f  this   Itox    is   two-fold,   it    increases   the   strength   of  the 

l>-irs    for   taking   bending  and  at  the   same  time  acts  as 

it.  rnal  drift  bracing. 

The  upper  wing,  which  is  in  one  piece,  runs  right  across, 

upported  on  struts  sloping  outwards  as  in  the  Sop- 

The  other  two  wings  each  have  a  centre  section 

igidly  attached  to  the  body,  the  middle  one  resting  on  the 

p  longerons  and  the  bottom  one  running  underneath  the 

wer    longerons,   an   aluminium    shield    streamlining  the 

>rmal   surface   presented   by   the   deep  flat   sides  of  this 

imr. 

From   the   illustrations   it   will  be  seen  that   the  gap   is 

Uy    small,    being    very    considerably    less    than    the 

liord.     The    inefficiency    thus   caused   is   partly   made   up 

staggering  the  wings  but  even  so  one  would  imag- 

ic  tin-  machine  to  be  somewhat  inefficient.      The  interfer- 

1  ing  to  too  close  spacing  of  the  wings  chiefly  affects 

ie  lift  co-efficient,  and  as   the  machine   is   probably   very 

:htly  loaded — compared  with  the  majority  of  German 

>'  bin.  s       it    is  possible  that  the  landing  speed  is  not 

Strictly    speaking,   the    Fokker   is   not   a   triplane.     It 


would  be  mon  correct  to  term  it  a  three-and-a-half  plane, 
as  the  wheel  avle  is  enclosi  d  in  i  .•  ising  of  plywood  which 

•M  soincMhat   similar  to  that  of  the  «  . 

p.rnnints   h.,\c  shown  Hint   floats  ,.|    ,uch  a  sift  ion  as  to 
ply   cambered   top   surface  may    be  made  to  sup- 
port  their   ,.wn    weight    during  flight.       In   the   case   of   the 
Fokker    triplane    it    ap|»  irs    probable    thai    tins    pi 

around  the  wheel  axh  ,  not   inconsiderable 

load  during  flight.      Its  section   ap|>«-ars  capable   „: 
porting  a   fair  load   per  square    foot   of  area,  and   its   in 
effici.  i  to   low    aspect    ratio   is   probably    less   than 

one  wo::!d  expect  in  a  plane  of  an  aspect  ratio  of  dmut 
two.  on  account  of  the  proximity  of  the  ,-ov, -red  in  wheels 
to  the  tips,  the  effect  of  which  must  he  to  stop  end  losses 
to  a  considerable  extent. 

As  regards  the  body  of  the  Fokker  triplane  tins  is  con- 
structinnally    very    similar   to   that    of    the    Fokker   mono 
I  lanes.      I  ongcrons    as    well    as    struts    and    cross    ni.in 
lers  are  in  the  form  of  steel  tubes,  and  are  joined  together 
by    welding.     The    internal    bracing   of   the    body    is    pe- 
culiar   in    that    the    bracing    wires    are    in    appearance    in 
duplicate,  although  they  are  not  so  in  effect. 

The  arrangement,  to  which  we  shall  revert  again  when 
dealing  with  the  Fokker  in  detail,  does  not  appear  to 
possess  any  other  advantage  than  that  in  each  bay  only 
half  the  nuinlMT  of  loops  II.IM  to  be  made  in  the  wires. 

The  tail  plane,  as  well  as  the  elevators  and  rudder, 
is  mode  of  steel,  and  is  of  a  symmetrical  section,  much 
thinner  than  that  of  the  Albatros,  but  otherwise  similar 
to  it  in  that  no  external  bracing  is  employed.  While  thin 
is  quite  satisfactory  in  the  Albatros  on  account  of  the 
thick  tail  plane  spars  employed,  it  appears  wholly  inade- 
quate in  the  Fokker,  as  the  plane  is  very  thin,  and  since, 
moreover,  the  trailing  edge  of  the  tail  plane  is  a  steel 
tube,  which  section,  as  is  well  known,  is  not  a  good  one 
for  •  laterally  loaded  beam,  owing  to  the  fact  that  much 
of  the  material  is  massed  around  close  to  the  neutral  axil 
where  it  in  not  taking  very  much  of  the  load. 

As  exhibited  at  the  F.ncmy  Aircraft  View  Rooms  the 
Fokker  is  not  complete  inasmuch  as  the  engine  has  been 
removed.  The  cowling  shows  without  a  doubt  that  tin- 
engine  must  have  been  a  rotary,  and  the  mounting 
the  type  usually  employed  for  rotary  engines,  i.e.,  a  main 
engine  plate  holted  to  the  nose  of  the  body .  and  a  pyramid 
of  steel  tubes,  supporting  at  its  apex  the  rear  end  of  the 
crank-shaft.  A  sheet  of  aluminium  is  placed  immediately 
in  front  of  the  engine  plate.  The  manner  of  cowling  in 
the  engine  will  be  apparent  from  our  illustrations,  and 
docs  not  present  anything  of  particular  interest,  follow- 
ing, as  it  does,  conventional  practice. 

Although  they  are  not  in  place  in  the  machine  M  ex- 
hibited, it  is  evident  from  the  aluminium  eastings  for  the 
cartridre  1  rlts  that  two  synehronis.  d  ni-ichine-giuiH  have 
hi  en  t.:-il,  one  on  en  h  side  above  the  fuselage.  The 
usual  tri;-:-i  rs.  operating  the  guns  through  How<!cn  cables, 
are  mounted  on  tie  control  lever,  which  latter  is  of  the 
usual  type. 

The  following  data  relating  to  the  weight  of  tin-  ma- 
chine is  given:  Wright  empty.  :t?ii  kg.,  useful  load,  195 
kg.,  total  weight,  371  kg.  (about  1830  \b».). 


226 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Front  view  of  the  early  form  of  Aeromarine  Seaplane,  showing  the  small  head-resistance 

The  Aeromarine  Training  Seaplane 


The  seaplane  is  substantially  the  same  as  the  land  trac- 
tor, except  that  the  seaplane  has  a  slight  increase  in  plane 
area. 

General  Dimensions 

Span,   upper   plane    \S  ft.  9  in. 

Span,  lower  plane M  ft.  0  in. 

Chord      6   ft.  3  in. 

Gap     6  ft.  6  in. 

28  ft.  9  in. 

Height  over  all    H  ft.  0  in. 

Weight,  empty    1,400  Ibs. 

Speed    range    77-43    m.p.h. 

Motor,  Hall  Scott  "  A7a  "  100  h.p. 

Dihedral  angle  of  wings,  1°;  Stagger,  1  ft.  6  in.  There 
is  no  becksweep.  Aspect  ratio  of  top  plane,  6.8 ;  lower 
plane,  5.4.  Wing  curve,  R.A.F.  6.  Plane  area,  not  in- 
cluding the  two  ailerons,  410  sq.  ft. 

The  body  is  22  ft.  6  in.  in  length ;  width,  34  in. ;  maxi- 
mum depth,  3  ft.  6  in.  Standard  dual  Dep  control  is  in- 
stalled. 

The  stabilizer  is  double  cambered,  non-lifting  and  non- 
adjustable;  area,  50  sq.  ft.  Area  of  rudder,  which  is  of 
the  balanced  type,  10  sq.  ft. 


Twin  pontoons  are  arranged  catamaran  style,  centered 
7  ft.  0  in.  apart.  They  are  of  the  hydroplane  type  with 
V  bottoms  and  rounded  sides  and  tops.  Length,  16  ft. 
6  in.;  beam,  30  in.;  depth  17  in.  A3  in.  step  occurs  7  ft. 
6  in.  from  the  rear  end  of  the  pontoon.  Air  leads  are 
built  in  to  reduce  the  vacuum  at  the  step. 

Material  of  pontoon  is  spruce,  ash  and  mahogany,  with 
double  diagonal  planking  having  layers  of  fabric  between. 
The  inside  is  divided  into  several  watertight  bulkheads. 

The  power  plant  in  the  machine  shown  in  the  accom- 
panying illustrations  consists  of  a  Hall-Scott  "  A7a  "  4 
cylinder,  vertical,  four-stroke  cycle,  rated  100  h.p.  at 
1400  r.p.m.  Bore  and  stroke,  5^4  in.  by  7  in.;  weight, 
410  Ibs.  Fuel  consumption  per  hour,  91/2  gallons.  Oil 
capacity  in  crankcase,  3  gallons.  Fuel  carried  for  a  flight 
of  4  hours'  duration.  The  propeller  is  8  ft.  4  in.  in  diam- 
eter. 

A  streamline  stack  discharges  the  exhaust  gases  from 
the  motor  over  the  top  of  upper  wing.  This  protects  the 
passengers  from  the  gas  and  keeps  the  machine  clean. 


Side    view    of   the   early    type    of    Aeromarine    Seaplane 


SINCLK   MOTOHKI)  A  Kl«  MM.ANKS 


•-"-'7 


I  KONT   \  II.U    01      1111.    I-"'   II. I'.     \l  I«>M AltINK   NAVY  TUAIMNC   SI.AI'1  AM. 

Thr  \rriim.iriin-  Navy  Training  Seaplane.  II  is  equipped  with  n  Cnrtiss  <>\  \<*>  horse-power  engine  or  the  Acromarlne 
1  in  Imrsr  power  I'liirinr.  This  seaplane  is  of  the  single  float  type,  a  development  of  the  Aeromiirlne  twin  float  Seaplane  which  ha* 
been  iiM-il  e\teiisi\ely  by  the  Navy  Department.  With  the  single  float  the  marhine  is  easy  to  manumrer  on  the  water 


Thr   Ai-roiiiiirinc   MiMlrl    1(>-T  Flyinfr  Boat  is  provided  with  a  100  horse-power  Curtiss  OX  enfrine.     This   mnrhine  has  Iwn  <lr- 
rd   I"  answiT   rri|iiiremrnt<i  of  thr  sportsman.     The   Aeromnrlne    130    hor-.e-|iower   Type    I,    engine    is    supplii-il    whrn    ilesin-il. 

Span  of  upper  plane  *8  fe.-t ;  chord,  7.i  in<-hcs;  pap,  78  in<hcs;  total   weight    19i5   pounds;   weight    fully   loaded,  i.483   pounds.     The 

wing  floats  have  a  buoyancy  of  £64  pounds.    32  gallons  of  gasoline  are  carried 


The  Aeromarine  "T-50"  Three  Seater  Flying  Boat 


1— Seating  arrangement,  showing  the  open  cockpit  for  the  pilot  and  the  two  rear  passengers'  seat*  enclosed  in  a  transparent 
cover,  which  protects  the  occupants  from  the  wind  and  spray.  The  casing  Is  divided  and  hinrcd  at  the  middle,  permitting  acceu 
from  either  side.  3  —  Stern  post,  rudder  hinges  and  hull  skid.  3  — Aileron  pulley  attached  to  the  lower  left  plane.  4  —  Engine 
IN. I.  and  attachment  of  middle  struts.  5—  Kighl  wing  float,  built  up  of  mahogany  veneer  with  an  ash  frame.  The  bracing  U  of 
steel  till*-,  faired  to  a  steamline  form 


228 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The   Boeing  Type   C-l-F   Seaplane 


Boeing  Seaplan< 

The  model  C-l-F  is  an  advanced  modification  of  the 
Boeing  type  "  C  "  seaplane  used  by  the  Navy  Depart- 
ment for  training  purposes  during  the  war.  This  ma- 
chine embodies  the  use  of  the  single  float  and  the  Curtiss 
OXX-2  eight-cylinder  motor.  A  further  modification  from 
the  "  C  "  type  lies  in  the  use  of  one  degree  of  dihedral 
rather  than  2%  degrees  as  used  on  the  older  machine. 

Wing  Structure 

The  wing  structure  follows  the  model  "  C  "  in  that  a 
50  per  cent,  stagger  and  21/-;  degree  declage  is  used.  This 
combination  assures  the  inherent  longitudinal  stability 
which  lias  been  characteristic  of  previous  Boeing  designs. 
The  center  cabane  struts  are  made  of  seamless  steel  tub- 
ing with  special  steer  terminals,  giving  a  simple,  efficient 
and  sturdy  center  section  construction.  The  forward  con- 
struction of  the  cabane  eliminates  fore  and  aft  stays  and 
furnishes  substantial  means  of  bracing  the  side  radiators. 
The  interplane  spruce  struts  are  of  straight  streamline 
form,  tapered  at  the  ends  to  accommodate  strut  sockets, 
while  the  internal  drift  struts  are  made  from  web  sec- 
tions, of  box  form.  The  wing  fittings  are  of  special  de- 
sign, giving  a  minimum  of  head  resistance,  while  provid- 
ing for  maximum  strength  necessary.  The  wing  tip  floats 
are  provided,  these  being  of  conventional  form  and  se- 
curely braced  to  the  lower  wings. 

Tail  Unit 

The  design  of  this  unit  is  characterized  by  extreme  sim- 
plicity as  well  as  maximum  strength.  Balanced  elevators 
are  used,  giving  automatic  adjustment  for  differences  in 
loading.  This  feature  is  particularly  notable  to  pilots  in 
that  maximum  and  minimum  conditions  in  the  distribution 
of  the  useful  load  are  unnoticed  in  flight.  The  elevators 
are  fixed  to  steel  shaft,  having  center  and  two  end  bear- 
ings for  supports.  Fin  and  tail  posts  are  of  steel,  mak- 
ing a  thoroughly  satisfactory  mounting  for  bracing  and 
tubes. 

Landing  Gear 

The  landing  gear  is  of  conventional  single  float  type. 
The  underwater  lines  of  this  float  are  such  as  to  asssure 
quick  get-away  and  easy  landing  without  undesirable 


-Type  C-l-F 

spray  and  water  disturbances.  The  stability  of  this  ma- 
chine has  frequently  been  demonstrated  while  taking  off', 
landing  and  taxying  in  rough  seas  and  while  drifting  in 
as  high  as  30-mile  winds.  The  float  is  of  two-ply  lami- 
nated construction  and  with  cotton  and  marine  glue  be- 
tween the  laminations.  The  external  float  fittings  are 
such  as  to  facilitate  rapid  assembly  as  well  as  to  trans- 
mit all  stresses  to  the  center  longitudinal  bulkhead,  which 
is  the  main  strength  member  of  the  float.  The  landing 
struts  are  of  streamline  steel  tubing. 

Body 

The  body  is  of  the  conventional  longeron  truss  type  with 
metal  frames  for  engine  bearers  and  metal  carry  through 
struts  for  lower  wings.  The  seats  are  made  from  a  series 
of  ash  slats  conforming  to  the  attitude  of  the  occupant 
and  covered  with  detachable  upholstery.  The  cushions 
are  stuffed  with  Kapoc  and  are  readily  detachable  for 
use  as  life  preservers  in  emergency.  The  instrument 
board  is  equipped  with  all  instruments  necessary  to  indi- 
cate the  operation  of  the  machine.  The  surface  control 


The  Boeing  Type  C-l-F   Seaplane 


SIMJI.K   MOTOUKI)   AKU01M.AM.N 


The     Hociiin     Type     III 

pi. in.-  «iili  Carttai  n\\  .-  mnt.i 


is   Dn.-il   Dep.-rdiissin.   featuring  an  adjustable  rudder  and  IP|HT   I'lan.-s   (includinir   Ailrrmis)    M4iq.ft. 

adjustable   rudder  compensator  for  distance  service       Tin-  I  "wer     I'lnn-     .                                                            .   £J9  »q.  ft. 

engine   throttle   is   mounted    a.    the    right   of   both   ebckpte,  Nu^.-f  Ail.-r *"'  " 

e  Ignition  retard  is  at  th<-  l.-ft  of  the  pilot's  cock-  Ki,-vat,.rx  aotq.rt. 

pit.      Tin-  ( Urtiss  OXX   J    MX)  li.p.  motor  has  proven  ex-  Hu<l«lrr    Uiq.ft. 

trrinrly    satisfactory.      It    is    lijfht,    powerful,    economical  Vertical    Kin    .  6  nq.  ft. 

and  fr.-r  from  undesirable  vibration  in  the  ranjp-  of  Hvinfc  3-  Or"''1"  l>imrn*iatu  — 

operation.      A  hand  starting  lever  is  provide,!  iminediatelv  Sp"n  ,ri>|K'r,1^'in'?    '                                            '   ** "     " 

,..,,.  •  .sp«n  Lower  \\  me U  ft.  11%  In. 

behind  the  motor  and  has  «„,.„  sat,sfactory  service.     As  ,-,„,„,  ,  ,,|M.r  n*d  ljomtT  wln)t 

Mentioned   before,   the   cooling  system   is  mounted  to  the  Gap   7.- in 

rear  and  above  the  motor.     This  mounting  is  exceptionally  l^-ntfth  over  all  .>:  n.  iii-p.  in. 

eOVetive  ; ind  l,as  performed  .satisfactorily  in  service.      The  H«-i|flit  ovrr  all  .                                                 .   I i  ft.  1 1  </,  to. 

IMS, .line   t.-mk   is   iuiinediatelv   Ix-hind   the  motor  and  sup-  '  <lr'» 

. .  . .  •  rtiAffrr    J9  yt  in. 

ph.s   gasoline  under  atmospheric  pressure    to   the  carbu-  Incidence  ,.f  up|K-r  wlnp   SV.drjf- 

retor.     The   carburetor   lead   is  supplied   with   a   shut-off  Incidence  of  lower  winjrn   tdr|r. 

%f«lve    operated    from    either    cockpit    as    well    as    a    con-  4.  I'rrfnrmnnrr  — 

\enient  drain  l.<  n<  atli  the  body  Climb  In  10  minutrx  (full  load)    IflOO  Frrt 

Mi^h  s|xf«l    TOM. P.M. 

Performance  Ijtndinir   snrrd    38  M.I' II 

I    l',,-,crr  Plant  -  Knduranrr  »t  full  uprrd  2%  hour* 

Curtiss  OXX-9   100  h.p.  5    Wright  — 

2.   H'IFK;  ami  I'unlrnl  Surfnrr  Arm* —  IJomded                                                                                     844S  lb* 

.Main   Planes    (including    Ailerons) 493 sq.  ft 


THEBUR.GE55  SEAPLANE 

MODEL     HT- 2 

SPEED     SCOUT 


5cale    of    feet 


McLaughlir 


230 


SI\(;i.K   MOTOHKl)  .\KK01M..\\ES 


•2-.ll 


The  Burgess  Speed  Scout 
Seaplane 


Tlirrr-<|iuirtrr   front  vlrw  of  the  Burgrai  »pe«l  tcoul  sraplanr 


Our  «f  tin-  neatest  scout  machines  of  American  manu- 
facture is  (In  Hurges.s  HT-2  .seaplane.  Tlie  Burgess  Com- 
pany's  experimental  works  ha.s  dcvvlo|ied  and  perfcetnl 
a  numlirr  of  original  construction  features  in  this  scout, 
the  must  -ipp.-irrnt  of  which  nre  the  struts  between  the 
planes  .-ind  td  tin-  Huats.  (he  shock-absorbing  float  system, 
and  a  detailed  elimination  of  sharp  angles  by  means  of 
li.-ils-i  umnl  streamlining. 

General  Specifications 

Winjr  span,   upper    3*  ft.  4  in. 

\Viii)T  sp.ni.   luwcr   il   ft.  6  in. 

\Viii(t   chord.   IM.HI    pl.mes    3  ft.  6  In. 

Gap    llrtweell     pliitles        4   ft.   0   in. 

Height   nvt-r   all    10  ft.  0  in. 

Ix-npth  oevr  »ll    -'-'  ft.  :«  in. 

M..l,,r.   Curtiss    OXX-J    100  h.p. 

Maxiniimi    speed    95  in.p.h. 

Lnndiiifr  speed    40  m.p.ti. 

Planes 

There  is  no  dihedral,  stagger  or  swecpback.  The  upper 
plane  is  in  four  sections,  the  central  sections  joined  by  a 
pair  of  metal  plates  at  the  wing  spars.  Each  section  1 1 
ft.  0  in.  long.  Outer  or  overhanging  sections,  to  which 
the  ailerons  are  attached,  are  each  5  ft.  10  in.  long. 

The  lower  plane  sections  extend  9  ft.  -I  in.  at  either  side 
of  the  fuselage,  which  is  SO  in.  wide  at  this  point.  Ribs 
are  spaced  9  in.  apart.  The  forward  main  spar  is  cen- 
tered 8  in.  from  leading  edge;  spars  centered  20  in.  apart; 
and  the  trailing  edge  is  1*  in.  from  the  center  of  rear 
spar.  This  totals  to  42  in.,  the  chord  of  the  plane. 

Internal  drift  wires  are  terminaled  to  the  ends  of  ta- 
pered compression  struts,  the  ribs  being  relieved  of  this 
strain.  Overhang  brace  wires  and  intcrplane  brace  wires 
are  doubled,  and  the  space  between  filled  with  spruce 
streamlining  strips,  the  edges  of  which  are  routed  out  to 
receive  the  wires. 

The  struts  are  K  shaped,  built  up  of  spruce  and  cov- 
ered with  fabric.  In  forming  the  strut,  one  spruce  member 
runs  from  below  the  upper  rear  wing  spar  to  top  of  lower 
forward  wing  spar;  another  member  runs  from  below 
upper  forward  spar  to  lower  rear  spar.  This  forms  an 
X  A  third  member  between  the  upper  and  lower  forward 
spars  gives  the  K  shape.  The  ends  are  filled  in  to  a 


HI,, I 


curve  with  balsa-wood,  doing  away  with  the  »n 
producing  a  streamline  effect. 

Body 

The  forward  part  is  covered  with  louvred  sheet  alumi- 
num in  the  usual  manner.  The  circular  radiator  at  the 
nose  is  27  in.  in  diameter.  The  sides  and  top  of  the 
body  arc  curved  beyond  the  longerons  by  means  of  thin 
horizontal  strips  of  spruce,  supported  on  formers,  and 
covered  with  fabric.  The  top  is  provided  with  a  semi- 
elliptical  streamlining  ridge  starting  at  the  pilot's  In  ul 
n-st.  The  top  of  the  body  is  in  sections,  which  are  sep- 
arately removable. 

The  pilot's  cockpit  is  exceptionally  deep  and  roomy. 
Deperdnssin  control  is  installed;  the  aileron  control  passes 
through  the  sides  of  the  body  at  a  point  12  inches  above 
the  lower  plane,  on  line  with  the  forward  edge  of  .struts. 
running  to  the  top  of  the  K  strut,  thence  to  a  pulley  at- 
tached to  the  underside  of  the  upper  wing  spar,  and  then 
to  the  aileron  crank.  Control  wire  openings  in  the  body 
are  protected  by  heavy  skin  washers,  sewed  to  the  fabric. 

The  cockpit  top,  above  the  instruments,  is  formed  with 
celluloid,  giving  ample  lighting  to  the  cockpit  interior 
and  at  the  same  time  providing  a  satisfactory  wind  shield. 

Tail  Group 

The  rear  spar  of  the  tail  plane  is  1 1  ft.  ()  in.  long. 
Solid  wire  braces  run  from  both  the  forward  and  rear 
spars  to  the  top  rear  end  of  the  vertical  fin,  and  also 
from  underneath  the  forward  spar  to  the  tail  float. 

The  root  of  the  vertical  fin  is  built  into  the  curved  fuse- 
lage top.  The  rudder  has  a  small  balancing  surface  for- 
ward of  the  hinges,  the  lines  of  the  rudder  continuing 
from  the  curve  of  the  fin. 

The  pair  of  stabilizers  are  attached  to  a  single  forward 
spar,  causing  them  to  work  in  unison.  Control  crank 
arms  are  9  in.  high,  with  a  pair  of  solid  brace  wires  to 
each. 

Floats 

Main  floats  are  11  ft.  0  in.  long,  3  ft.  0  in.  wide  and 
17  in.  in  maximum  depth.  They  are  spaced  6  ft.  6  in. 
from  center  to  center.  The  forward  horizontal  strut  be- 
tween the  floats  is  located  2  ft.  2  in.  from  the  bow,  and 
the  rear  strut,  which  acts  as  a  shock-absorbing  axle,  7  ft. 


232 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Side   view   of   the    Burgess    UT-2   speed 
scout    seaplane 


2  in.  from  the  bow.  Struts  run  from  the  forward  hori- 
zontal strut  to  points  near  the  radiator.  The  rear  axle 
is  at  the  lower  termination  of  the  V  struts,  which  run 
from  the  fuselage  and  the  lower  plane,  continued  in  the 
K  strut  to  the  top  plane.  This  axle  is  attached  to  the 
float  by  rubber  cord,  with  metal  guides  to  allow  for  the 
vertical  movement  of  the  axle.  By  means  of  this  system 
of  shock  absorbing,  much  of  the  porpoising  has  been 
eliminated  when  taxi-ing,  and  many  of  the  hard  landings 
are  entirely  taken  up  by  it. 

Hand  holds  are  provided  at  each  compartment,  screwed 
flush  with  the  deck.  Mooring  rings  are  attached  at  the 
forward  end  of  each  float.  A  step  occurs  just  below  tl-e 
rear  axle  with  a  2  in.  air  duct  run  through  the  float  to 
prevent  suction. 

The  main  support  for  the  tail  float  is  provided  in  a 
26  in.  extension  of  the  fuselage  termination  which  is 
streamlined  fore  and  aft,  to  a  width  of  7%  in.  A  pair 
of  struts  24  in.  long  are  located  15  in.  from  the  front 
of  tail  float,  and  bracing  wires  run  from  their  upper 


The  shock-absorbing  float  support 

ends  to  the  lower  end  of  rear  strut.     Overall  length  of 
pontoon,  4  ft.  6  in.,  width  ll1/^  'n->  depth  12  in. 

Motor  Group 

The  propeller,  designed  by  the  Burgess  Company  es- 
pecially for  the  speed  scout,  is  7  ft.  9  in.  in  diameter, 
with  a  5  ft.  9  in.  pitch.  The  motor  is  a  Curtiss  OXX-2 
rated  100  h.p.  at  1400  r.p.m.  Fuel  is  carried  for  a  flight 
of  2*A  hours'  duration. 


Curtiss  Model  H-A  Mail  Machine.  Streamline  has  been  carried  to  a  very  effective  degree  on  the  Curtiss  Model  H-A  Mail 
Machine.  The  fuselage  is  exceptionally  deep,  wings  being  attached  directly  to  the  fuselage  and  a  single  pair  of  struts  at  either 
side.  A  Kirkham  model  K-12  engine  is  used,  connected  to  a  four  bladed  propeller  with  high  pitch.  The  photograph  fhows  the  neat 
way  in  which  exterior  control  wires  have  been  eliminated. 


SINUI.K   MUTOKKI)   A  Kl{<  )1M..\NKS 


I  In-  I  'nrti-s  Mmli-l  1 1- A  1 1\  dm  An  unusual  fr.iture  in  this  III.H  him-  is  ||M-  sinjrlr  pair  of  struts  from  thr  pontiMia  In  tin-  fiisrlagr, 
tin-  dr<-|>  liody  anil  tin-  cliiiiiiiiitinn  of  struts  lx-t«rcn  tin-  wii>|is  ami  Inxly.  Thr  II|>|»T  ]>lanr  hits  the  customary  (xisjtjvr  ilili.-.lr.il  hut 
the  Inw.-r  planes  slo|..-  downward  in  n  negntivi-  or  rrvrrsrd  dihedral.  Thr  Hydro  rr«rinli|rs  in  many  respects  thr  H-.\  l-and  Ma- 
<-liim-  l>nt  two  sets  of  struts  iirr  used  on  thr  Hydro  l>ecmisr  of  the  greater  span. 


The  Curtis*  H-A  Hydro 


Tin-  (  nrtiss  II  \  Ilvilni  is  a  two  plan  single  flont  sea- 
l>lain-.  Tin-  upper  wing  has  ••>  dihedral  of  Sr  and  the 
lowi  r  pl.-uir  a  i-atlii-ilral  of  1°.  Both  plant's  have  an  in- 
rnlrnri-  of  .'  .  a  ml  a  swri-pliack  of  t'j  .  In  official  tests 
l<\  tin  \  ,\  \  I  >•  partiiu-nt  tins  inncl)ine  ha.s  made  a  sprcil 
of  l.il.'i  miles  per  hour  with  a  full  load.  Its  climbing 
spi  .  il  li  S.'.IMI  t,  it  in  ti-n  iniiiiiti-s. 

1  hi  final  is  jii  f.Tt  long,  .H  ft.  6  in.  wide  and  4  ft.  6  in. 
ili  i  p.  It  has  thri'i-  planini;  strps. 

The  horizontal  .stahilixer  is  adjustable  during  flight, 
within  tin-  limits  of  minus  and  plus  1°.  The  machine 
i-arrii  s  four  machinr-giins;  two  fixed  Marlins  and  two 
hYxilih  I.i  w  is 

Th.    rimiiii-   has   a    Liberty    1'-'.   giving  330  h.p.      It   is 
<lir.-.-tlv  eoniieetrd  to  a  two-hladrd  propeller  9  ft.  -J  in.  in 
di  uneti-r.  with  a  7   ft.  7  in.  pitch,  or  a  three-bladed  pro 
peller  s   ft.  ti  in.  in  diameter  and  7  ft.  6  in.  in  pitch,  de- 
pending upon  whether  speed  or  quick  climb  is  required. 

The  general  specifications  are  as  follows: 


l'l>l>er  plnne   ....................................  30  ft. 

l.owrr   plnne    ....................................    36    ft 

Cord     ...........................................   7*  in, 


Maximum  ftp 

Minimum   (rnp    ...................................    4i'/, 

Overall  hriffht    ...................................    10   ft 

(  Id-mil  Irnnth   ...................................   30  ft 

Arrn,  upper  plnne   ...............  •  •  IM.fl 

A  rrn,  lower  plnne    ...............................  170.8 

Total  siip|Ktrtlnf(  area   ...........................  390 

A  rrn  of  rach  nlleron  .............................     8.6 

Totnl  nllrron  nrrn    ..........................          .   34.* 

I  lorinnntal   -t.iliiliwr   .............................   M 

Vrrtlrnl   stnhlltaer    ...............................   18J 

Itucltler    .........................................    l«-'i 


o  In. 

0    in 

in. 
In. 

7    In. 

9  In. 
«,.  ft. 
«,.  ft. 

V|       ft. 

-I   ft 

«,.  ft. 

»q.  ft 
M|.  ft. 
»q.  ft. 


Weights 

Welftht  per  .sq.  ft »-3i  H>s. 

Wei(rht  per  h.p H-4     !••«• 

Nrt   wrlfrht,  machine  empty   1,6218          Ihs. 

Weiirht,  full  load   I.OI8         H». 

Performance 

Speed  range   6i  to  131.9  m.p.h. 

Climb    1,000   ft.   per   minute 


Thr    Curtis.,    Model    II-A     Hydro    aeroplane,    which    is    rnted  to  hive   a   »perd    range   of    from   61   to    130  mile*   per   hour 


,330  HP  LIBERTY 

FLYING   BOAT 


Jci.le  of  feet 


10        a        14        I 


234 


SIXCLK   MOTOKK1)   A  KK<  )I>I  ..\  M  S 


An   IIS  -'  I.  anil  other  types  of  American  flying  boats  mid  seaplanes  taking  off  in  formation 


Curtiss   Model  HS-2-L  Flying   Boat 

In  order  to  increase  the  amount  of  load  carried,  the 
MS  I  f.  type  of  mncliine  was  given  additional  wing  sur- 
f  in  .-uid  tliii-.  l«r:mie  the  IIS  v.'  I..  The  speed  was  not 
r<ili:i-.-d  liy  tliis  change.  The  climbing  power  was  con- 

-ider.-ililv   increased. 


General  Dimensions 

iii^   S|.:ui        fpper    IManr    74  ft.  0>%j  In. 

ine   Span  -  Lower   Plane   64  ft.   121;fe,  In. 

Depth  of  Wine  rhoril    6    ft.   3%,   In. 

dap  U-twccn  Wine*  (front)   7  ft.  7%   in. 

Cap  ln-tween  Wines   (rear)    7  ft.  52%2  In. 

_•!•  r    None 

Length  of  Machine- overall  40ft. 

Height  of  Machine  overall  14  ft.  7'/4   In. 

Alible  of  Incidence       t'pper  Plane  51/,   degrees 

le  of  Incidence  —  I.ower  Plane   4  degrees 

Dihedral  Angle  2  degrees 

;ihack    0  degrees 

ine   CIIMC     R.   A.   F.   No.   6 

Horizontal  Stabilizer— Angle  of  Incidence 0  degrees 

Areas 

-  I'pper    380.32  sq.  ft. 

-  I-ower     314.92  sq.    ft. 

Ailerons   (upper  62.88;  lower  42.48)    105.36   sq.   ft. 

Horizontal    Stabilizer    54.8  sq.   ft. 

Vertical  Stabilizer   19.6  sq.   ft. 

tor,  (each  J.'.s  sq.  ft.)   45.6  sq.   ft. 

Rudder    -'•'•5  sq.   ». 

I  Supporting  Surface  8O0.6  sq.  ft. 

»g  (weight  carried  per  sq.  ft.  of  support-  7.77  Ibi. 

ne  surface)    

Loading  (per   r.h.p.)    18.84  Ibs. 


Weights 

\.t   Weight  —  Machine  F.mpty    4,349  Ibs. 

Gross  Weight  —  Machine  and  Load 8.M3   Ibs. 

Useful  I^ad    1^64  Ibs. 

Kurl     977  Ibs. 

Crew    360  Ibs. 

Useful  loud   .  527  Ibs. 


Total    1.864  Ibs. 

Performance 

Speed  —  Maximum  —  Horizontal  Flight  91  miles  per  hour 
Speed  —  Minimum  —  Horizontal  Flight  54  miles  per  hour 
( •limbing  Speed  1,800  feet  in  10  minutes 

Motor 
I.ilH-rty  1 -.'-Cylinder.  Vee.  Four-Stroke  Cycle  ....  Water   cooled 

Horse' Power   (Rated)    ' 330 

Weight  per  rated  Horse  Power  3.55  Ibs. 

Bore  and  Stroke  5  In.  x  7  In. 

Fuel  Consumption  per   Hour   32  gals. 

Kurl   Tank   Capacity    152.8  gals. 

Oil  Tank  Capacity   8  gals. 

Fuel  Consumption  per   Brake   Horse   Power  per 

Hour     0.57  Ibs. 

Oil   Consumption    per   Brake    Horse    Power   per 

Hour     0.03  Ibs. 

Propeller 

Material      Wood 

Pitch  —  according  to  requirements  of  performance. 
Diameter  —  according  to   requirements  of  performance. 
Direction  of  Rotation  (viewed  from  pilot's  seat)    Clockwise 

Maximum  Range 
At  economic  speed,  about  575  miles. 


Front  view  of  the  HS-2-L  equipped  with  a  Liberty  "IS"  motor 


236 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Curtiss  Model  HS-1,  which   was  the  forerunner  of  tin-       The  Curtiss  Model   HS-1  in  flight,  making  a  speed  of   76   mile 
HS  2-L  an  nour 


The  HS  J-L,  equipped  with  a  Liberty  motor.  The  wing  spread  of  the  HS  1-1-  was  in- 
creased to  lift  a  greater  load.  A  counterbalanced  rudder  was  also  added.  This  type 
of  machine  was  used  for  patrol  duty  in  this  country  and  also  as  a  training  plane  for  the 
pilots  of  the  H-16  and  F  5-L  boats. 


Side  view  of  the  HS  2-1..  It  has  been  found  that  only  one  set  of  ailerons  on  the 
upper  wing  only  is  sufficient  to  handle  the  machine.  The  use  of  this  boat  for  combat 
purposes  is  limited  because  of  its  unprotected  rear  portion.  As  a  patrol  scout  it  car- 
ried two  bombs,  beneath  the  lower  wing,  one  on  each  side  of  the  hull.  The  crew  con- 
sists of  two  pilots  and  an  observer  in  the  front  cockpit 


IOOHPCURTISSCKX 

FLYING  BOAT 

ScaJ«  of   feet 


•Mn-Hn 


237 


238 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


CURTISS  MODEL  M.   F. 
FLYING  BOAT 

The  Navy  Department  has  em- 
ployed a  great  number  of  the  M. 
F.  Boats  for  coastal  training 
work.  Machine  is  well  suited  for 
marine  sportsmen  for  it  is  com- 
paratively small  and  is  easily 
handled.  The  boat  is  provided 
with  either  a  Curtiss  OX  5  100  h.p. 
engine  or  the  new  Kirkham  K-6 
150  h.p.  six-cylinder  vertical  en- 
gine. The  M.  F.  Boat  is  an  im- 
provement in  design  over  the  Cur- 
tiss F  Boat  which  found  so  much 
favor  before  the  war  stopped 
civilian  flying 


Curtiss  Model  MF  Flying  Boat 


This  machine  is  suitable  for  general  and  sporting  use. 
It  is  an  improved  form  of  the  F  boat. 

General  Dimensions 

Wing  Span  -  Upper  Plane   •  «  «.  9%  in 

Wing  Span  —  Lower  Plane 38   «•    '%2   >' 

Depth  of  Wing  Chord   .  > 6' 

Gap  between  Wings  at  Engine  Section  6^  ft    4%4   i 

Length  of'  Machine'  overall  ".'.'.'.'.'.'.'.'.'.'. 28  ft.   W«  in. 

Height  of  Machine  overall   11  ft.  9%  to. 

Angle  of  Incidence   "  degrees 

Dihedral  Angle,  Lower  Panels  only   2  degrees 

Sweepback    Xone 

Wing  Curve  U-  «.   A.  No.  1 

Horizontal  Stabilizer  —  Angle  of  Incidence   ...  0  degrees 


Areas 

Wings  —  Upper    

Wings  —  Lower     

Ailerons  (each  22.43  sq.  ft 

Horizontal    Stabilizer    

Vertical  Stabilizer   

Elevators  (each  15.165  sq.  ft.)   

Rudder    

Total   Supporting   Surface    

Loading  (weight  carried  per  sq.  ft.  of  support- 
ing surface)     

Loading  (per  r.h.p.)    


187.54    sq.    ft. 
169.10    sq.    ft. 
44.86    sq.    ft. 
33.36    sq.    ft. 
15.74    sq.    ft. 
30.33    sq.    ft. 
20.42    sq.    ft. 
401.50    sq.    ft. 
6.05  Ibs. 

24.32  Ibs. 


Weights 
Net  Weight  —  Machine  Empty   ...............   1.796  Ibs. 

Gross  Weight  —  Machine  and  Load   ...........   2,432  Ibs. 

Useful  Load    ...............................  •   ^6  Ibs. 

Fuel     .............................     ^°     lbs' 

22'51bs- 
3fi      lbs' 


Oil 
Water 


Pilot          ..........................     16S      lbs' 


Passenger     

Miscellaneous   Accessories    

Total 636.0  lbs. 

Performance 

Speed  —  Maximum  —  Horizontal  Flight  69  miles  per  hour 
Speed  —  Minimum  —  Horizontal  Flight  45  miles  per  hour 
Climbing  Speed  5,000  feet  in  27  minutes 

Motor 
Model     OXX  —  8-Cylinder,     Vee,      Four-Stroke  Water   cooled 

Cycle     

Horse  Power  (Rated)  at  1,400  r.p.m B 

Weight  per  rated  Horse  Power  *-01 

Bore  and  Stroke  

Fuel  Consumption  per  Hour    1' 

Fuel  Tank  Capacity  *°  g"ls- 

Oil  Capacity  Provided  —  Crankcase   

Fuel   Consumption   per   Brake    Horse   Power  per 

Hour     ....    °-60   lbs' 

Oil   Consumption    per    Brake    Horse    Power   per 

Hour     ...    °-030lbs- 

Propeller 

Material      •  Wood 

Pitch  —  according  to  requirements  of  performance. 
Diameter  —  according  to  requirements  of  performance. 
Direction    of    Rotation     (as    view    from    pilot's 
seat)      Clockwise 

Details 

Dual  Control. 

Standard  Equipment  —  Tachometer,  oil  gauge,  gasoln 

Maximum  Range 
A',  economic  speed,  about  325  miles. 


SINCil.K   MOTOKK1)   AKHOIM.AN  KS 


..         • 


I  In    Inn  I,  p    l.ilxTty  motored  (iallnndet  !)-•  lijjlit  1'iuiilxT  -enplane 


The  Gallaudet  D-4  Light  Bomber  Seaplane 


Tin-  Gallaudet  D-J  Light  Bomber  Seaplane  uses  a 
single  KK>  li.p.  Liberty  "  Twelve  "  engine. 

Si  \ir.il  n-tiiu -incuts  in  detail  have  Ix-en  incorporated 
in  the  IK  w  design,  ..,M,l  it  is  probable  that  the  Gallaudet 
is  now  tin  fastest  sr.-iplnne  ever  built.  Its  maneuver- 
ability is  exceptionally  flexible,  in  spite  of  difficulties 
usually  encountered  in  seaplane  design. 

On  Deeeinber  IsJth  a  series  .if  tests  of  the  !)-»•  Sea- 
plane were  carried  out  during  a  two-hour  run  over  Narra- 
gansi  It  Hay  liy  the  I'.  S.  Navy.  The  tests  show  the  ma- 
chine to  be  capable  of  cruising  at  78  miles  an  hour,  while 
the  engine  turned  at  1360  r.p.m.  At  this  speed  the  fuel 
consumption  was  16  gallons  per  hour,  and  the  cruising 
radius  7.19  hours,  in  which  time  a  distance  of  561  miles 

could    lie   emered. 

General  Specifications 

Span,   upper  plane   16   ft.  6   in. 

ClK.nl.    Ix.th    planes    7   ft  0  In. 

t  ween  planes   7  ft.  0  in. 

Total  winjf  area   6H  sq.    ft 

Wrijrht.  iimchinr  empty   3JWX)   ll». 

•  of  useful  load  ' 1.600    \\>-. 

Wri^ht.   fully   loaded    i,4OO  Ibs. 


Maximum   sprrd    I  .'(i  m.p.h. 

Slowest    landing:    4.'. li  m.p.h. 

Slowest    p-taway    46.0  m.|>.h. 

Climb  in  two  niinutr*   J.UMI  ft. 

Klyinjf  rndiu.s  at   full  power   3  hours 

The  useful  load  is  made  up  of  the  following: 

Water    I  l.i  Ibs. 

Pilot   and   observer    :«O  Ihs. 

Fuel  and  oil    (UO  Ibs. 

( Irdnance     9.5  Ibs. 

Bombs   390  Ibs. 


Total     1600  ll.s. 

The  fuselage  is  of  streamline  form,  with  a  circular  iec- 
tion  bullet  nose.  Steel  tuliinjf  is  employed  in  the  frame- 
work. 

At  the  forward  end  the  gunner's  cockpit  is  located.  A 
flexible  searfed  ring  for  mounting  twin  Lewis  machine- 
guns  is  placed  around  the  cockpit.  A  very  wide  are  of 
fire  is  provided  for  the  gunner,  and  an  unobstructed  view 
is  obtained  by  both  pilot  and  gunner. 

The  engine  is  located  aft  of  the  pilot,  between  the  up 
per  and  lower  planes.      It  drives  a   ring  surrounding  the 


The   GMlaudet    D-4   leaving   the 
water     for     a     flight.     Note     the 
•>  i'  k  of  the  wings 


•240 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


fuselage,  to  which  the  four-bladed  propeller  is  attached. 

This  construction  is  unique  in  that  it  permits  the  ad- 
vantages of  an  enclosed  fuselage  usually  employed  in 
tractor  machines,  while  the  screw  is  placed  in  pusher 
position,  permitting  an  advantageous  placing  of  occupants 
and  engine. 

Planes  are  flat  in  span  and  similar  in  plan,  but  ailerons 
are  placed  on  the  upper  plane  only.  Planes  have  a  mod- 
erate stagger  and  a  pronounced  sweepback. 

The  center  section  of  the  upper  plane  contains  a  38 
gallon  fuel  tank  with  a  supply  pipe  running  straight  down 
to  the  engine  below  it. 

A  75-gallon  fuel  tank  is  placed  in  the  main  float  at  the 
center  of  gravity.  The  fuel  system  employs  twin  wind- 
mill pumps  with  overflow  return. 

Two  radiators  are  located  in  the  center  section  at  either 
side  of  the  gravity  fuel  tank.  They  are  set  into  and  con- 
form in  outline  to  the  wing  section. 

Central  pontoon  or  main  float  is  built  up  of  mahogany. 
It  has  16  water-tight  bulkheads  or  compartments.  The 
two  wing  tip  floats  each  have  five  compartments. 


GALLAUDET  D-4  BOMBER 

The  Giillaudet  Bomber  has  a  Lib- 
erty Engine  of  400  h.p.  driving  a 
four-bladed  pusher  propeller.  The 
machine  is  a  two-seater  with  pilot  and 
observer  placed  well  forward.  Fuse- 
lage finely  streamlined  and  the  plac- 
ing of  the  lower  wings  below  the 
fuselage  brings  the  center  of  thrust  in 
a  very  desirable  location.  A  maxi- 
mum speed  of  126  m.p.h.  and  a  climb 
of  2,100  feet  in  2  minutes  was  re- 
corded in  an  official  test  flight 


The  Gallaudet  D-4  in  flight  over  Narragansett  Bay 


The  Curtiss  K-9  Seaplane,  equipped  with  the  Curtiss  V-2  200  h.p.  motor 


SIMiLK   MOTOKK1)   .\KHUIM..\NKS 


Typ< 


Thomas-Morse 
-S-5  Single-seater  Seaplane 


Gener?!  Dimensions 


I.cnjrtli 
Spread 

II.  it-lit 


.'.'ft    'tin. 

.''.  ft.  '•  in. 

!l  ft.    T  in. 


Weight  and  Lift  Data 

Total   weight   loaded    1500  Ibs. 

Arm  lifting  surface   (including  ailerons)    JiO  sq.ft. 

Loading  per  square  font  nf  lifting  surface   6.::>   HIS. 

Keijuired   horse   power   105 

eight  i>f  in.irhiiir  loaded  IMT  h.p U.:i  His. 

.Power  Plant 
Type  nf  engine    100-h.p.  Cinornr   (air  cooled  rotary) 

n^'ine    rrMiliitiniiK    |i«T    liiinuti-    

Furl   capacity,  'Mi  (.'all. ins.  sufficient    for  :{  liours'   Hijfht  at   full 

power 

Oil  capacity.  ii..'i   gallons,  sufficient   fur  .'!'_.   liours'   flight   at  full 

poucr 

rn>|M-lliT  t\  pi-     3  blade 

I'niprlliT  diameter    8   ft. 

Propeller  rcMilutions  |>rr  minute   1350 


Chassis 


Ty  I  M 


.Twin  |M>ntiMins  and  tall  float 


Area  Control  Surfaces 

Ailerons:    (two)     30      sq.ft. 

Klrv  aturs     ii      gq.  ft. 


The  Thomas-Morsr  S-i  Seaplane  about  to  make  a  lundlng. 
Motor:  Gnome  100  h.p. 


f«.S  sq  ft. 

Horixontal  stahiltcer   16.H  tq.  ft. 

Vertical  stabiliser    3.5  «q.  ft. 

Stick  type  control  used. 

Performance 

speed    93  milrs  ]HT  hour 

speed  M  mile*  per  hour 

Climb  in  first  trn  minutes  6JOO  ft. 


Navy  M-2  Baby  Seaplane 


Tin  \l  j  S,  -ipl.-uif  d,  M^'ii.'d  by  the  Navy  Department 
as  1. 1  hn.  !><  t  M  used  for  sulimarine  patrol  work.  It  in 
tli<-  sui  ill.  st  s,  ,-iplane  ever  built,  and  its  size  has  gained 
for  it  thr  ii.iini'  of  "  niolrrule."  It  is  easily  set  up  and, 

eupyin^  -ii  little  space,  can  be  stored  aboard  a  sub- 
iiiariiu-. 

Tin-  in.-u  liiii.-  is  a  tractor  monoplane  with  twin  floats. 
The  |il  uir  has  a  span  of  19  ft.,  a  chord  of  -I  ft.,  and  n 
total  w  iii>r  aren  of  only  72  square  feet.  The  wing  section 
is  a  modified  K.A.F.  15.  Overall  length  of  machine  13 
ft. 

Tin-  floats  .-ire  10  feet  long  and  weigh  16  Ibs.  each. 
I'lii  \  are  eoiistructed  of  sheet  aluminum  with  welded 
seams.  The  interior  of  the  floats  is  coated  with  glue 


and  outside  is  not  painted  but  coated  with  oil.  F.xperi- 
ments  have  proven  this  practice  to  be  most  efficient  in 
preventing  corrosion.  Floats  have  exceptional  reserve 
buoyancy:  with  machine  at  rest  on  the  water  it  i-.  ini 
possible  to  overturn  machine  by  standing  on  the  wings 
near  the  tips  or  by  standing  on  the  rear  of  the  fuselage. 

The  engine  is  a  S  cylinder  Ijiwrence  60  h.p.  air  cooled 
engine,  driving  a  6  ft.  6  in.  propeller  with  a  5  ft.  pitch. 
12  gallons  of  gasoline  and  I  gallon  of  oil  are  carried, 
sufficient  for  •.'  hours'  flight.  Fully  loaded  with  pilot  and 
fuel  the  complete  machine  weighs  but  .ion  pounds.  The 
maximum  speed  is  about  100  m.p.h.,  and  the  low  s|>eed  is 
.'>(>  m.p.h. 


The   Curtiss    R-«   twin   pontoon 

rap). in.-   equipped    with   a   C'urtivs 

-I  lip.  motor 


THE  FRENCH  FB.A 

HISWO-SUIZA  MOWED 

FLYING   BOAT 


Sc.l.     of     f«t 


Mclaughlin 


242 


SIN(;i,K   MOTOMK1)  AKK01M.AM  - 


TIli-    I •'.    B       \.    11}  in,;    boat,       lln 
t>pe    nf    liu.-it    u.i^    useil    extensively 
fur   over-water    lifililiii);    In    the  al- 
lies,  iinil   lias   proved    MT\    sitisfac- 
lurx . 


The  F.  B.  A.  Flying  Boat 


This  boat,  equipped  with  Gnome .  Clcrget  or  niorr  often 
Ilispaiio-Sui/a  en-m.  s.  In-  pro\ ed  In  !><•  fast  anil  «.l! 
suited  fur  lii-li  speed  coastal  Hying.  All  the  Allii-s.  lint 
more  p:irtinil;irly  Franc.-  and  Italy,  largely  used  the  FBA 
!>(>  it-,  fur  en  er  water  fighting,  and  much  good  work  has 
IHTII  dune  with  it. 


General  Specifications 

Spin,     upp,-r     plain-     47ft.  614  in. 

Span,   lower    plane    3i  ft.  8-Tf,  In. 

Clniril,  upper  plain-   6  ft.  £•{,  In. 

Clinril.   lower  plane    iff.  :J  in. 

Cap    between    planes    5  ft.  9%;,  in. 

Length    overall     33  ft.  :«,,;  in. 

•  t   overall    10  ft.  8U,  in. 

Net    weight,   machine  empty    150O  Ihs. 

iiross  weight,  machine  and  load   1600  Ibs. 

Knjrine,  Ilispano  Suiza   150  h.p. 

Propeller,  iliameter   ft  ft.  6  in. 

Speed     ranjre     99-45  m.p.h. 

('limbing  speed    3300  ft.  per  min. 


Main  Planes 

Main  planes  are  not  staggered  and  have  no  sweephack 
nor    dihedral.      Fnd.s    are    raked    at    a    13°    angle.      In,  i 
1, nee  angle  of  upper  and  lower  planes,  3°. 

L'pper  plane  is  in  three  Dictions;  lower  plane  also  in 
:hree  sections.  1'pjx-r  and  lower  center  wing  panels  are 
7  ft.  8:ts  in.  long.  I'pper  outer  panels  19  ft.  10%  in. 
ong;  lower  outer  panels  \'t  ft.  ()  in. 

Centers  of  inner  interplane  struts  located  8  ft.  9  3/16 
n.  to  either  .side  of  the  centerline  of  the  aeroplane;  inter 
nediate  struts  centered  5  ft.  •-.'  13/16  in.  from  inner  struts; 
niter  struts  centered  6  ft.  8  in.  from  intermediate  struts. 
Slanting  struts  carrying  the  overhang  of  the  upper  wing 
lave  their  upper  ends  centered  5  ft.  1 1  in.  from  outer 
•truts.  This  leaves  a  2  ft.  7  1/16  in.  overhang  at  each 
ring-tip.  Overhang  on  the  lower  wing.  2  ft.  73/16  in. 

Chord  of  the  upper  plane.  6  ft.  2~'s  in.  Front  wing 
warn  centered  7~x  '"•  from  leading  edge;  beams  centered 
!  ft.  II  7 '16  in.  apart.  Distance  from  center  of  rear 
icam  to  rear  of  trailing  edge,  2  ft.  7  916  in. 

Chord  of  the  lower  plane,  5  ft.  3  in.  Beam  spacing 
rom  the  leading  edge  is  similar  to  that  of  the  upper 


plane.  Distance  from  the  center  of  rear  beam  to  tin- 
trailing  edge.  1  ft.  7  7  16  in. 

Ailerons  on  the  upper  outer  wing  sections  are  2  ft. 
7  !»  Hi  in.  wide  and  H  ft.  I  i:>  1C,  in.  in  spnn. 

For  propeller  clearance  the  upper  plane  is  cut  away 
for  9  ft.  10:ls  in.;  from  the  lower  plane  a  portion  4  ft 
.S'o  in.  wide  is  cut  away. 


Hull 

Overall  length  of  the  hull,  30  ft.  2  I  16  in.;  maximum 
width,  at  rear  of  cockpit,  t  ft.  33/16  in.  The  planing 
step  on  the  bottom  of  the  hull  occurs  10  ft.  (>>*  in.  from 
the  nose.  The  nose  extends  8  ft.  6-%  in.  forward  of  the 
leading  edge  of  the  wings.  Bracing  rabies  run  from  the 
nose  to  the  tops  of  forward  intermediate  interplane  struts. 

Provisions  are  made  for  carrying  a  pilot  and  passenger 
seated  side-by-side  in  the  rear  cockpit,  and  a  passenger 
or  gunner  in  a  cockpit  forward  in  the  hull. 

Wing-tip  floats  arc  placed  directly  below  the  outer  hi- 
terplanc  wing  struts. 


Empennage 

The  empannage  or  tail  group  is  supported  by  a  set  of 
.struts  from  the  upturned  termination  of  the  hull.  The 
horizontal  stabilizer  is  set  at  •  slight  positive  angle.  It 
is  semi-oval  in  outline,  its  front  edge  located  it  ft.  I  I  :<  16 
in.  from  the  trailing  edge  of  the  main  planes.  From  front 
edge  to  trailing  edge  it  measures  5  ft.  2  13/16  in. 

The  elevator  or  tail  flap  consists  of  a  single  hinged 
surface  3  ft.  117  16  in.  wide  and  8  ft.  In'^.  in.  in  span. 
It  is  actuated  by  two  pairs  of  small  diameter  tubular  steel 
pylons  at  either  side  of  the  rudder. 

The  rudder,  of  the  balanced  type,  is  mounted  above 
the  tail  on  a  pivot  situated  I  ft.  1 '  j  in.  forward  of  the 
tail  flap.  It  extends  |u  <i  1(5  in.  forward  of  the  pivot  and 
3  ft.  11  7/16  in.  aft  of  the  pivot.  This  brings  the  rear 
edge  of  the  rudder  6  9/16  in.  beyond  the  tail  flap  trailing 
edge. 

Four  bracing  wires  run  from  the  top  of  the  rudder  pivot 
to  points  where  the  tail  is  supported  from  the  hull.  Con- 
trol wires  to  the  rudder  and  tail  flap  run  into  the  hull 
through  a  single  control  wire  outlet  in  the  deck. 


244 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The    Italian    Savoia    Verduzio    168    h.p. 
Reconnaissance   flying  boat 


The  Italian  Macchi  Flying  Boat.  The 
total  surfaces  are  supported  upon  struts 
and  braces. 


GEORGES  LEVY 

TYPE  R  *">«»RfNlUlT 

FLYING    60AT 


M«tr 


McLikujklin 


245 


246 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


The  Georges  Levy  Type  R  Flying  Boat,  equipped  with  a  280  h.p.  Renault  Engine.  Span,  upper  plane,  18.5  meters;  lower, 
12  meters;  total  length,  12.4  m.;  overall  height,  3.85  m.;  lifting  surface,  68  sq.  meters;  stagger,  138  mm.  .5;  weight  empty,  1450 
kg.;  useful  load,  1000  kg.;  speed,  145  km.  per  hour. 


Method  of  folding  the  wings  of  the  Georges  Levy  Type  R  flying  boat 


The  Georges  Levy  two-seater  flying  boat  "  Alert,"  with  a  Hispano-Suiza   engine.     This   is   a  lighter  boat   than  the  Type   R. 

Both  types  have  the  folding  wing  feature. 


AUSTRIAN  AGO  TYPE 

210   H.P.  

5EA  PURSUIT  BIPLANE 


Scat.    <f  M.t* 


247 


248 


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Austrian  Ago  Flying  Boat 


In  its  general  lines  this  machine  does  not  differ  much 
from  all  the  flying  boats  of  the  Ago  type.  It  does  offer, 
however,  features  that  are  original  and  worthy  of  men- 
tion. Most  striking  is  the  structure  of  the  wing  cell  in 
which  no  wires  are  employed. 

The  wing  cell  may  be  considered  as  consisting  of  two 
cross-networks,  each  made  up  of  a  front  spar  and  a  rear 
spar  and  of  adjacent  struts  in  inclined  planes  connect- 
ing the  spars,  all  converging  toward  the  center  of  the 
"  star  "  located  midway  between  upper  and  lower  wings. 
The  struts  are  of  polished  steel  tubing  with  a  fairing  of 
laminated  wood  less  than  one  mm.  thick,  providing  a  good 
streamlining  effect. 

General  Dimensions 

Span,   upper   plane    8.00  meters 

Span,  lower  plane    7.38  meters 

Chord,  both  planes  1.50  meters 

Gap  between  planes    1.65  meters 

Length    overall    7.62  meters 

Length  of  hull    6.50  meters 

Maximum  width  of  hull   1.00  meter 

Motor,    Warschalowski     218  h.p. 

Propeller,  diameter    2.72  meters 

No  lists  of  weights  or  performances  are  obtainable. 

Control  cables  to  the  ailerons  pass  close  to  the  struts 
of  the  turret  and  lead  to  the  upper  plane.  Each  aileron 
is  about  1.40  meters  long  and  .40  meters  wide. 

The  construction  solution  of  the  hull,  the  great  care 
with  which  the  exposed  parts  have  been  shaped,  the  com- 
plete covering  of  the  cables  and  control  wires,  and  the 
streamline  shape  of  the  hull,  all  show  a  desire  to  cut  down 
head  resistances  as  much  as  possible.  Similar  care  is 
shown  in  all  details  of  construction  to  reduce  to  a  mini- 
mum the  weight  of  the  machine  without  detriment  to  its 
strength. 

The  hull  is  6l/->  meters  long;  vidth  at  the  step,  .95 
meters;  maximum  width,  1  meter;  distance  from  bow  to 
step,  8.45  meters;  height  of  step,  .16  meters.  The  shape 
of  the  body  wtth  the  necessary  lining  .at  the  bow  and 
because  of  a  careful  laying  of  the  side  and  bottom  plating 
approaches  very  much  the  shape  of  a  solid  body  of  fairly 
good  streamline  form.  The  wing  floats  are  spaced  5 
meters  a"art.  They  are  of  streamline  section,  with  flat 
sides,  attached  to  the  planes  by  means  of  one  forward 


strut  and  two  rear  struts,  with  cross  wire  bracing  be- 
tween the  struts. 

The  empennage  or  tail  group  is  2.38  meters  in  span, 
sustained  in  front  by  a  vertical  fin  of  very  thin  laminated 
wood,  by  two  stays  and  two  wire  cables.  Control  wires  of 
the  rudder  flaps  or  elevators  run  through  the  fin.  The 
rudder  is  1.40  meters  high  by  .80  meters  wide. 

The  data  -given  out  concerning  the  motor  is  as  follows : 
"  Motor:  Hiero  Flugmotor,  Osterr;  Ind.  Werke  Wars- 
chalowski, Eissler  &  Co.;  A-G  6  cylinders;  type  HN1096. 
It  develops  218  h.p.  at  1400  revolutions  per  minute. 
Weight  314  kilograms.  It  is  equipped  with  Bosch  mag- 
netos and  small  starting  magnetos.  Propeller:  200 
h.p.h.  Hiero  6  cylinders;  diameter,  2.72  meters;  pitch, 
2.25-2.40." 


Sketch  showing  the  Austrian-Ago  Sea-Pursuit  Biplane  "  A-25 ' 
in  flight 


SINCI.K   MOTOKKI)   A  KU<  >1M  .  A  \  I   - 


l.olui.-r  l-'ljinjr  Moat  lc:t\  inp  for  a  flight.     Steel  tiil.irij:   plai  ~  ,ui  ii.i|x.rlaiil  part  in  Hi.   .oust  ruction  of  this  machine 

The  Lohner  Flying  Boat 


This  is  an  enlarged  machine  of  the  Lohnrr  type,  retain- 
ing tin-  \'  which  is  typical  of  the  Lohner  aeroplanes. 
There  .in-  six  steel  struts  on  either  side  and,  two  by  two, 
.ire  connected  in  transverse  pl.-ines  with  steel  tubes  of 
Hi  mm.  outside  diameter.  The  distance  between  two 
struts  in  the  direction  of  the  brace  is  1.30  meters,  and  in 
the  direction  of  Ihe  spar  2.17  meters. 

General  Dimensions 

Sp.m,  upper  plane   9.70  meters 

Sp.ni.    lower    plane    7.3)  mrtrrs 

<  hcinl.   upper   pi. me    2.70  meter* 

<  linril,    lower    pliinr    2.M  mrtrrs 

Mull.   iii.-i\iiiiiiiii   length    li.iO  mrtrrs 

Hiniili    carrying    capacity     400    kg. 

Motor,    \n-tro  Dataller    soo  h.p. 

Iii  form  the  ailerons  .in-  tr.-ipcxoidal,  like  that  of  the 
It.-ili  in  I.olmcr  machines.  Length  of  ailerons,  .S.17  me- 

mi  an   width.  .!>()  meters. 
Dinii  iiMons  of  the  empennage  or  tail  group:      Length 


of  horizontal  .stabilizer  or  tail-plane,  4.74  meters;  width, 
ni-tiTs.      Length  of  tail-flaps  or  elevators,  4.71  me 
ters;    width,    O.87    meters.     The    vertical    rudder    differs 
from  that  of  the  old  1  ohm  r  machines  in  that  there  is  • 
small  balancing  area  forward  of  the  pivot. 

The  principal  dimensions  of  the  hull  are:  Maximum 
width,  1.50  meters;  maximum  length,  li.SO  meters;  maxi- 
mum height.  l.iO  meters;  step,  .25  meters. 

The  body  has  two  seats  side  by  side  and  one  in  front, 
upon  which  is  mounted  a  machine-gun  arranged  to  be 
movable  and  fired  in  any  direction.  Beside  the  pilot,  next 
to  tin-  observer,  there  is  also  a  machine-gun  arranged  on 
a  movable  tube  inside  the  casing.  The  outside  tube  is 
the  only  additional  piece  the  machine  contains. 

The   turret    is    armored.     No    bomb-dropping    d< 
have    been    located.     There    are    two    vertical    pieces    of 
wood,  with  a  circular  profile  notch  fastened  to  the  floats 
under  the  wings.     It  may  be  that  these  are  used  to  drop 
large  bombs,  but  no  discovery  li  i*  been  made  which  would 


The  winn  float  used  on  the  "  K-301,"  an  Austrian  S-seatrr  flying  boat  of  the  l-ohnrr  typr 


250 


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A  close  up  view  of  a  German  flying 
boat,  showing  some  new  features  of 
construction.  Steel  tubing  is  used 
extensively.  The  wing  top  floats  are 
also  of  unusual  design 


show  how  they  are  secured  in  them.     Several  hooks  for 
small  bombs  were  found. 

The  lateral  or  wing-floats,  instead  of  being  hemispher- 
ical in  shape,  have  a  bow  with  good  streamlines,  which 
plow  on  the  water  surface  like  the  prow  of  a  ship.  The 


accompanying  drawing  shows  their  general  outlines.     Each 
is  88  cm.  wide  and  181  cm.  long. 

The  engine,  an  Austro-Daimler,  lias   12   cylinders  a 
ranged  in  a  V.     It  is  rated  at  300  h.p. 


CIIAl'TKK    IV 


AEROPLANE  AND  SEAPLANE  ENGINEERING 

Bv    <  OMMANUEK    H.   ('.    UK  inn s     I      >     \ 


Tin-  problem  confronting  tin  Navy  was  largely  detcr- 
inilii-il  ;it  tin-  time  tin-  I'nitcd  States  entered  thr  w:ir  by 
tin  fact  tli:it  tin  operations  uf  tin-  (iiTinari  and  Au-.tn.in 
Hi  ets  I,  i.l  lii  i-ii  riiliu-iil  |iritn-i|i.-ill\  to  minor  ranis  fnun 
tin-  Heel  bases  ,-it  Kill  and  I'ola.  ami  tin  only  real  sea- 
going operations  comprised  the  activity  of  subnmriin  I, 

Tin-  work  uf  tin-  si-a|il:iin  s.  tlicrcforc.  was  prim  mlv 
reduced  to  that  uf  cooperation  with  the  fleet  in  reducing 
the  submarine  menace.  This  naturally  led  to  the  estab- 
lishment of  coastal  .stations  in  France.  Italy.  F.ngland. 
Scotland  and  Inland.  In  these  operations  it  was  pos-i 
blc  to  operate  seaplanes  from  shore  banes  in  practically 
every  CMC,  ami  the  development  of  work  with  the  fleet 
U-c.-ime  a  minor  consideration. 

-••mi-  of  the  seaplane  bases,  however,  werr  sufficiently 
clnse  tu  enemy  territory  to  \w  within  raiding  distance  of 
enemy  planes  of  both  land  and  water  tyjK's.  and  it  Ix-canic 
necessary  for  the  Navy  to  extend  its  activities  to  the  use 
of  land  planes  for  the  protection  of  seaplane  bases,  while 
naval  aviators  also  participated  in  big  bombing  raids  on 
(iiriimn  and  Austrian  territory. 

I  refer  to  these  matters  in  this  grncrnl  way,  not  to  de- 
scribe tin  activities,  but  to  show  that  in  naval  work  both 
land  and  water  planes  were  used,  and  why  the  Xavy  prob- 
lem was  in  general  restricted  to  opi  ration  from  shore 
bases  rather  than  operation  from  ships.  Activities,  how- 
ever, were  not  confined  to  shore  bases  in  Kurope.  Sta- 
tions were  established  on  the  Atlantic  const,  principally 
for  the  purpose  of  submarine  patrol  and  for  convoy  work 
from  the  principal  ports  from  whieh  our  troops  and  sup- 
plies were  sent  abroad. 

Type*  of  Planes  Developed 

The  work  of  seaplanes  abroad  was  that  of  submarine 
patrol  and  convoy  work,  and  this  having  been  determined 
on.  all  efforts  were  made  to  obtain  the  most  suitable 
seaplanes  for  the  service.  The  principal  work  was  done 
with  two  tv|N-s  of  seaplanes,  namely,  the  IIS-v!  tin-  sin- 
notored  plane  develo|x-d  from  the  IIS-1  • — and  the 
H-lfi.  a  copy  of  the  Knglish  seaplane  of  the  same  type 
il>  v  eloped  as  a  result  of  Commander  1'orte's  cx|>cricnce 
with  tin-  original  America  and  subsequent  types  devel- 
oped therefrom.  Finally,  the  F-.'i-I.  type  was  developed 
from  F.nglish  designs  for  manufacture  in  this  country  by 
the  Naval  Aircraft  Factory  at  Philadelphia.  The  ||> 
and  the  H-lfi  have  proved  well  suited  to  the  work  re- 
quired, but  the  F-5-L  did  not  enter  production  early 
enough  to  get  into  active  service  before  the  armistice  was 
red. 

The  Navy  did  not  attempt  to  develop  land  plane  types. 
but  accepted  and  used  those  which  had  been  developed 

2.-.  I 


nnd    produced    for   tin     Army,   adopting    for   this    purposi 
iirlish    llandley-Page.   the    Italian   Caproni.   and   the 
Army   Dll    I  and   DM  0 

In  order  that  pilots  should  be  trained  for  this  s. r\  n  • 
it  was  necessary  to  adopt  training  planes,  and  for  this 
purpose  the  \avy  developed  and  used  the  Curtiss  \  • 
the  H  ti  nnd  the  |{  :i.  the  Aeromarine  and  Hoeing  sea- 
planes, and  the  F-boat.  and  also  i  \perimeiiti  d  with  n 
number  of  miscellaneous  types,  such  as  the  (iiiome  scouts 
both  biplane  and  triplanc  of  Curtiss  and  Thomas  man- 
ufacture—  and  the  (iallaudet  \)-.'>.  The  most  successful 
of  these  training  planes  was  the  N-!i,  particularly  after 
the  original  float  had  Ix-en  modified  and  Inter  on  after 
the  substitution  of  the  Hispano  13O-li.p.  engine  for  the 
O.XX  loo-h.p.  engine.  This  plane  was  a  biplane  tractor 
with  a  single  center  float,  having  wing  tip  balancing  floats. 
It  was  remarkably  strong  and  could  perform  practically 
all  sorts  of  maneuvers.  Although  in  training  work  it  was 
frequently  wrecked,  then-  were  remarkably  few  deaths 
resulting.  This  I  attribute  to  its  moderate  s|>ccd.  great 
strength  of  construction  and  tractor  arrangement,  which 
made  it  suitable  for  training  purposes. 

As  soon  as  it  was  determined  that  seaplanes  of  the 
flying-boat  type  were  to  IM-  used  in  service  it  became  nee 
essary  to  provide  preliminary  training  in  a  type  of  sea- 
plane which  more  nearly  represented  the  conditions  of 
operation  of  the  big  boats.  For  this  purpose  the  F-boat 
originally  developed  by  Curtiss  for  sporting  and  for  naval 
use  was  modified  and  adapted  to  instruction  purposes. 

I  shall  later  on  describe  and  illustrate  the  principal 
types  referred  to. 

So  far  as  the  aerodynamical  and  mechanical  features 
of  construction  are  concerned,  seaplanes  differ  very  little 
from  airplanes,  the  principal  difference  being  the  use  of 
the  landing  gear  suited  to  operation  from  the  surface 
of  the  water  instead  of  from  the  land.  The  proportions 
are.  naturally,  somewhat  different,  and  the  performance 
is  different,  primarily,  because  of  the  great  inertia  due 
to  the  increased  weight  involved  in  the  seaplane  construc- 
tion. But  bearing  this  in  mind,  the  details  of  construc- 
tion of  seaplanes  are  substantially  the  same  as  those  used 
in  airplanes. 

Factors  Affecting  Performance 

It  will  now  be  of  interest  to  consider  the  principal 
factors  which  affect  performance,  ns  it  is  necessary  to 
understand  these  completely  to  develop  a  design  which 
shall  perform  according  to  the  requirements  of  tin  service 
intended.  For  the  purpose  of  illust rating  the  factors 
involved  I  have  prepared  a  set  of  performance  curves, 
which  I  believe  will  give  a  clear  insight  into  this  phase 


252 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


of  the  problem.  The  complete  calculation  of  the  curves 
shown  is  given  in  the  Appendix,  together  with  the  formu- 
las involved  in  the  computations. 

The  performance  in  power  flight  is  determined  by  t 
horsepower  required  and  the  horsepower  available,  and, 
of  course,  the  latter  must   always  exceed  the   former   ( 
power  flight  is  not  attainable. 

In  determining  the  powei  required  there  are  two  prin- 
cipal factors  involved.  The  first  factor  is  that  of  the 
horsepower  required  to  propel  the  planes  with  their  load 
in  flight.  This  horsepower  I  term  the  plane's  e.h.p. 
determine  it,  it  is  necessary  to  know  the  form  and  dis 
position  of  the  wing  surfaces  used,  as  well  as  the  aero- 
dynamic characteristics  of  the  wing  section  employed 
The  lifting  power  of  the  wing  depends. on  the  area  and 
the  square  of  the  speed  of  advance,  and  its  resistance 
is  also  in  proportion  to  the  area  and  the  square  of  the 
speed  of  advance,  the  speed  of  advance  being  the  speed 
relative  to  the  air  itself  and  not  the  speed  over  the 
ground. 

The  lift  of  an  airplane  surface  and  its  resistance  to 
advance  are  determined  by  the  lift  and  drift  factors, 
which  vary  with  the  type  of  section  used  and  also  with 
the 'angle  of  attack  at  which  the  surface  is  presented 
to  the  relative  stream  of  air.  It  has  been  found  by  ex- 
periment that  these  factors  are  influenced  by  the  propor- 
tion and  arrangement  of  the  surfaces,  the  best  results 
being  attained  with  what  is  known  as  the  monoplane 
surface. 

Performance  is  improved  by  increasing  the  dimension 
of  the  wings  in  the  lateral  sense,  over  that  of  the  fore- 
and-aft  dimension.  The  ratio  of  these  two  dimensions 
is  called  the  aspect  ratio.  As  the  aspect  ratio  is  in- 
creased, it  is  found  that  the  efficiency  is  improved  indefi- 
nitely. But  after  an  aspect  ratio  of  8  or  10  is  attained 
the  improvement  in  efficiency  becomes  less  and  less,  and, 
practically,  is  not  worth  going  after,  because  the  dimen- 
sions become  unwieldy  and  the  gain  in  lifting  power  and 
efficiency  may  be  more  than  wiped  out,  due  to  the  in- 
creased weight  and  resistance  of  the  structure  required 
in  employing  it.  It  is  largely  on  account  of  this  diffi- 
culty that  the  biplane  and  the  triplane  have  been  used 
where  large  lifting  power  is  required,  even  though  in 
the  latter  cases  the  efficiency  of  the  surfaces  is  reduced 
because  of  interference  of  the  air  flow,  which  is  found  to 
depend  upon  the  gap  ratio.  By  this  is  meant  the  ratio  of 
the  distance  between  superposed  planes  to  the  chord 
length,  or  fore-and-aft  dimension  of  the  wings. 

Where  the  leading  edge  of  the  upper  plane  is  forward 
of  the  leading  edge  of  the  lower  plane  the  efficiency  is 
improved  over  that  where  one  plane  is  immediately  above 
the  other,  and  conversely.  This  arrangement  is  referred 
to  as  stagger  and  the  condition  of  positive  stagger,  that 
is,  with  the  upper  wing  forward  of  the  lower  wing,  is 
generally  adopted  with  the  view  of  improving  efficiency. 
There  are  limits  to  its  usefulness  because  of  the  obliquity 
of  the  trussing  involved. 

Stagger  may  be  adopted  for  various  reasons,  such  as 
correcting  the  balance  of  an  airplane  in  which  the  actual 
location  of  the  center  of  gravity  does  not  conform  to  that 
originally  contemplated,  or  in  order  to  improve  the  view 
of  the  pilot  or  observer,  particularly  if  the  latter  is  also 
a  gunner. 


The  efficiency  is  improved  if  the  upper  plane  has  a 
greater  lateral  dimension  than  the  lower  plane.  This  dis- 
position is  known  as  overhang.  There  are  limits  to  the 
extent  to  which  this  can  be  employed,  on  account  of  the 
structural  difficulties  involved. 

In  the  normal  type  of  construction,  the  front  and  rear 
edges  of  the  wings  are  parallel,  although  it  is  found  that 
tapering  the  wings  to  a  smaller  fore-and-aft  dimension 
at  the  wing  tip  improves  efficiency.  This  arrangement  is 
not  satisfactory  from  a  manufacturing  point  of  view,  as 
it  involves  different  sized  ribs  at  every  station  in  the 
wings.  All  the  above  considerations  have  to  be  taken 
into  account  in  determining  the  form  and  proportion  of 
the  wing  surfaces. 

Another  factor  is  very  important,  that  is  the  travel 
of  the  center  of  pressure  on  the  wing  surfaces.  It  is 
found  that  where  wings  have  a  cambered  surface  —  which 
is  usual  in  airplane  construction  because  of  the  superior 
lifting  power  —  the  movement  of  the  center  of  pressure 
is  such  as  to  cause  longitudinal  instability.  Various 
devices  have  to  be  employed  to  overcome  this.  The  most 
satisfactory  and  usual  method  is  to  employ  an  auxilliary 
surface  at  the  tail  of  the  airplane  called  the  horizontal 
stabilizer,  and  the  best  conditions  for  stability  are  found 
when  this  rear  surface  has  a  smaller  angle  of  attack 
than  the  wing  surfaces  themselves. 

This  difference  of  angle  between  the  wings  and  tin- 
horizontal  stabilizer  is  termed  "  longitudinal  dihedral." 
The  stiffness  or  steadiness  of  an  airplane  in  flight  de- 
pends on  the  area,  proportion,  section  and  angle  of  tin- 
rear  surface.  Where  great  stift'ness  is  desired,  this  rear 
surface  may  even  assume  the  proportions  of  a  second  set 
of  lifting  surfaces  which  may  be  of  monoplane  or  biplane 
arrangement,  usually  of  smaller  dimensions  than  the  main 


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Typical  Motor  Characteristic   and  Propeller   Efficiency  ("urv< 


.\KK01M..\\K   AM)   SEAPLANE    K. Mil  \KKKI\c. 


planes.  Where  the  rear  surfaces  are  increased  to  ncarlv 
tin-  proportions  of  tin-  forward  surfaces,  the  tnndciu 
biplane  arrangement  is  approached. 

For    military    purposes    ami    for    combating    rough    air 
conditions   it    is    foiiml   ilrsjralili-    to   lia\r   initial    loiigitudi 
ii  ii    stability,   lint    it    is   undesirable   to   have   tins   in     ,    hiijli 
decree    on    a    military    plain-    in    wliicli    steadiness    mav    I* 
essential   to  tin-   propi-r  operation  of  a  gun  or  of  a  luimli 
dropping    device.      If    (In     r.  ar    surface   were    completely 
ti\«l  in  nil!  i, in  In  the  forward  surface  it   would  be  possi- 
l>lr   to   proceed    in    liori/ontal    flight    at    our   definite 
only    for   tin-    load   carried,   and    ascending   or   desi •ending 
could    he   accomplished    only    by    increasing   or    di  --re-ism  ; 
the  power,  or  1>\   de, Teasing  or  in. Teasing  (he  Jnad.      These 
methods   of  eontrol  are   not   sufficient  lv  accurate  or  active, 
and    it    is    nmeh    more    satisfactory    to   use    additional   sur- 
known  a>  eh  -valors,  appended  to  the  rear  margin  of 
the    hori/.ontal    stal ili/.cr.    which    by    modifying   the 
of  the  stabilizer  make  it   possible  to  proceed  in  horizontal 
flight    at    any    speed    from   the   minimum   to   the   maximum 
Ihiii;;  speid.  or  to  i-anse  the  plane  to  rise  or  descend.       In 

iirpiains.  in  order  to  get   the  maximum  of  r 
vcring   ahility.    the    hori/.ontal    stabilizer    is    reduced    to    a 
\rry    small    area:    or.    e\eii.    in    some    cases,    is    completely 

d  with,  all  being  merged  in  the  elevator. 
In    the    original    Wright    machine    lateral    balance    was 
maintain. -d    hy    warping    the    wings,    but    this    ir.'!:cd    i» 
unfavorable   to  strength   in   Inrp-  structures.  ai:d   t.'ie   use 
of  ailerons   for  this   purpose  I. as   n   w   h.-comc  ;•   :i--rnl. 

In    flight,    airplanes    are    not    always    operatic!    so    that 
the  trajectory  conforms  to  the  axis  of  the  airp! -lie,  par- 
ticularly  when   turning  or   when  encountering  side   g  :sts, 
As  a  consequence,  unless  what  is  known  as  the  keel 
siiriace   of   the   airplane   is   distributed  equally  above  and 
In-low    tin    center  of  gravity,  there  is  a   tendency   for  the 
airplane  to  roll  one  way  or  the  other,  depending  upon  the 
location  of  the  center  of  gravity  relative  to  tlie  center  of 
lateral    pn  ssiire.      To    compensate    for    this    cti'cct.   or   to 
provide  lateral  stiffness  under  such  conditions,  it   is  usual 
tn  provide  a  moderate  amount  of  what  is  known  as  lateral 
dihedral:  that  is.  the  winir,  tips  are  higher  than  the  center 
iiortion  of  the  wings;  or  else  skid  tins  are  placed   i:n:;: 
lintch    under  or  above   tin-   upper  wings.      These  in  gen- 
ral  have  the  same  effect  as  lateral  dihedral.      Hy  modify- 
ing   this    arrangement     the    amount    of    lateral    stability 
can  be  controlled  to  any  desired  degree.      Again  for  mili- 
irv    purposes   it    is   desirable   to   have   initial   lateral   sta- 
lility.  but   not   to  such  a  degree  as  to  interfere  with  con- 
rol! ability  of  lateral  balance. 

Directional  stability  is  also  affected  by  the  lo.-ati-n  of 
he  center  of  side  pressure,  depending  upon  its  location 
fore-and-aft  of  tile  center  of  gravity.  It  is  essential  for 
!y  (light  that  the  center  of  lateral  pressure  at  small 
ngles  of  skew  should  not  pass  forward  of  the  center 
>f  gravity.  To  accomplish  this  it  is  usually  necessary  to 
nstall  a  vertical  stabilizer  at  the  tail  of  the  airplane.  It 
s  again  desirable  to  have  initial  directional  stability. 
\nd  again,  in  a  military  plane,  it  is  undesirable  to  have 
his  to  such  a  degree  as  to  interfere  with  control  of 
lirection.  As  the  airplane  is  symmetrical  relative  to  the 
vertical  fore-and-aft  plane,  it  is  unnecessary  to  provide 
my  equivalent  of  the  dihedral  effect,  and  it  is  only  n-ees- 
ary  to  append  a  rudder  to  the  vertical  stabiliser  in  order 


10     JO     M    40    M    80     70    M     00  100 


10    20     30    tO     80     00     TO     HO     W    100  110  I'M  130  110 
I  lorsrpower  Curves  of  Ihp   KAKtf   Kiplnnr 

to  control  direction.  In  some  planes,  where  extreme  ma- 
u<  uveral  ility  is  desired.  Uie  rudder  itself,  in  its  neutral 
position,  performs  the  functions  of  a  vertical  stabilizer 
as  well  na  that  of  a  rudder,  and  no  vertical  fixed  surface 

is    used. 

Location  of  Powerplant  and  Crew 

1 1  iv  in::  given  due  consideration  to  the  influence  of  the 
proportion,  arrangement  anil  dispositio-i  of  the  main  siip- 
porting  and  control  surfaces,  it  is  m-x'  n -n  ss.-.rv  to  eon 
sidcr  the  service  intended  and  the  location  of  (he  power- 
plant  and  the  crew.  The  possible  arrangements  arc  al- 
most infinite,  but  in  general  it  is  desirable  to  locate  the 
pilot  centrally  where  he  will  have  a  proper  view  to  enable 
him  to  handle  the  airplane  to  the  greatest  advantage,  and 
this  is  particularly  necessary  in  the  combat  plane.  It  is 
also  essential  that  the  gunner  shall  have  an  large  and 
unobstructed  a  view  as  practicable,  and  that  with  the  gun 
positions  selected  he  shall  IK-  able  to  cover  his  are  of 
fire  and  as  much  of  the  surrounding  sphere  as  is  prac- 
ticable, in  order  that  there  shall  Ix-  no  dead  spots  from 
which  the  enemy  may  approach  without  his  being  able 
to  return  the  fire.  This  sometimes  requires  that  the  pilot 
himself  sh  ill  be  able  to  operate  guns  firing  dead-ahead, 
or  that  additional  gunners  shall  Ix-  placed  so  that  they 
can  cover  area  of  fire  not  possible  for  the  others  to 

cover. 

In  bombing  planes  and.  in  particular,  in  night  bombing 

ones,  this  requirement  is  of  less  importance,  and  the 
requirement  that  the  lx>mh  dropper  shall  have  a  pro|XT 
view  for  the  operation  of  the  bomb  sights  become*  of 
prime  iin|tortancc. 

In    airplanes   di  -signed    for    long-distance    flights   or   for 


254 


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bombing,  it  becomes  necessary  to  have  great  power  avail- 
able, and  this  requirement  has  led  to  the  adoption  of  mul- 
tiple unit  powerplants.  Two,  three,  and  as  many  as  five 
powerplants  have  been  successfully  used  for  this  pur- 
pose. The  multiple-engine  plane  has  the  advantage  that 
in  case  of  damage  to  one  powerplant  it  is  usually  possible 
to  continue  flight  with  those  remaining;  or,  if  still  too 
heavily  loaded  to  accomplish  this,  it  is  possible  to  glide 
for  a  long  distance  and  thereby  select  a  more  favorable 
landing  place,  and  often  to  avoid  landing  on  enemy  terri- 
tory. 

All  these  and  many  other  considerations  enter  into  the 
disposition  and  arrangement  of  the  powerplant  and  fuse- 
lages, and  these  arrangements  themselves  have  an  influ- 
ence on  the  performance  of  the  wing  surfaces  because  of 
interferences  involved. 

By  winging  out  the  powerplants  a  more  favorable  load 
distribution  is  imposed  on  the  airplane  structure  and  ad- 
vantage is  taken  of  this  feature  in  designing  the  wing 
trussing.  The  effects  of  interferences  and  of  the  dispo- 
sition and  proportion  of  the  wings  or  bodies  and  auxil- 
iary surfaces  are  so  complex  that  unless  data  are  already 
available  from  similar  designs,  it  is  very  desirable  that 
the  resistance  and  lifting  power  of  the  complete  design 
should  be  determined  from  wind-tunnel  tests  of  a  model 
carefully  constructed  to  scale  in  every  detail.  Such  model 
test  is  usually  deferred  until  the  design  has  approached 
some  definite  form  after  preliminary  estimates  have  shown 
that  it  is  capable  of  approaching  the  performance  desired. 

Form  and  Proportion  of  Wings 

In  preliminary  estimates  the  influence  of  the  form  and 
proportion  of  the  wings  is  carefully  estimated,  and  from 
these  estimates  a  fairly  accurate  approximation  of  the 
horsepower  required  for  the  planes  is  derived.  To  arrive 
at  the  total  horsepower  required,  it  is  next  necessary  to 
consider  the  horsepower  required  to  overcome  the  head 
resistance.  In  order  to  do  so,  it  is  necessary  to  have 
accurate  knowledge  of  the  resistance  of  all  elements  of 
the  airplane  structure  exclusive  of  the  wings,  which  are 
exposed  to  the  action  of  the  wind  in  flight. 

To  reduce  the  resistance  of  these  elements  to  a  mini- 
mum, streamline  forms  are  adopted  wherever  practicable, 
and  even  the  truss  wiring  is  made  up  of  streamline  form; 
or,  if  this  is  not  found  practicable  these  wires  are  cov- 
ered with  false  streamline  covers  of  wood  or  metal.  It 
is  found  that  the  reduction  in  resistance  more  than  com- 
pensates for  the  additional  weight  involved  in  applying 
these  false  covers. 

The  resistance  of  the  fuselages,  radiators,  engines,  tail 
control  surfaces,  elevator  rudder,  aileron  horns  and  all 
other  elements  is  computed  in  detail,  and  account  is 
also  taken  of  the  obliquity  of  these  elements  to  the  flow 
of  the  air.  Such  obliquity  is  found  to  exert  an  important 
influence  on  their  action.  For  preliminary  estimates,  it 
is  customary  to  determine  the  resistance  of  these  elements 
for  the  position  assumed  by  them  at  some  speed  inter- 
mediate to  the  low  flying  speed  and  to  the  high  speed 
attainable  with  full  power,  and  then  to  assume  that  the 
resistance  of  these  elements  is  proportional  to  the  square 
of  the  speed  for  speeds  above  and  below  the  intermediate 
speeds  selected.  This  is  most  handily  done  by  assuming 


that  the  resistance  of  these  elements  is  represented  by  a 
flat  surface  exposed  normal  to  the  wind,  which  would 
have  the  same  resistance  as  the  aggregate  of  these  ele- 
ments. This  supposititious  surface  is  what  is  referred 
to  when  we  speak  of  the  "  surface  of  equivalent  head  re- 
sistance." In  the  example  which  I  have  chosen  to  illus- 
trate, "  the  equivalent  head  resistance  "  is  assumed  to  be 
20  sq.  ft.,  and  the  horsepower  required  to  drive  this  head 
resistance  through  the  air  is  indicated  on  the  curve  de- 
noted head  resistance  horsepower.  By  compounding  the 
ordinates  of  this  curve  with  the  ordinates  of  the  plane's 
e.h.p.  curve  we  derive  the  total  e.h.p.  required  curve. 

We  have  next  to  determine  the  total  brake  horsepower 
available  in  order  to  determine  the  performance  of  the 
airplane.  To  determine  this  curve,  we  must  first  know 
the  full-throttle  characteristic  of  the  engines  to  be  used. 
This  characteristic  is  indicated  in  the  example  showing 
the  brake  horsepower  available  at  different  speeds. 

The  next  thing  to  be  determined,  and  the  one  having 
a  most  important  influence  on  the  performance  of  the 


T|T  Tp 1 1 1 1 1 

ttltolMHtMIM 

Chart  for  Determining  the  Dimensions  of  Propellers 

airplane,  is  the  propeller  characteristic.  To  date  the 
progress  in  propeller  design  has  been  far  from  satis- 
factory, and  although  good  results  have  been  obtained, 
the  best  results  possible  have  seldom  been  approached.  In 
the  selection  of  the  propeller,  one  of  the  first  considera- 
tions is  to  determine  what  feature  of  performance  is 
most  important,  for  it  is  necessary  to  select  the  proper 
dimensions  with  a  view  to  gaining  the  best  results  for 
the  service  intended.  For  instance,  if  high  speed  is  of 
greatest  importance,  the  propeller  to  be  selected  will  differ 
materially  from  that  which  would  be  required  if  great 
climbing  power  is  desired,  because  the  greatest  climbing 
power  will  be  attained  at  a  speed  much  lower  than  the 
maximum  rate.  Or,  it  may  be  a  question  of  selecting! 
a  propeller  which  will  give  the  greatest  efficiency  at  cruis- 
ing speed,  and  this  propeller  will  usually  differ  from  that 
selected  in  either  of  the  preceding  cases.  In  some  case* 
it  may  be  desirable  to  select  a  propeller  which  will  give 
the  best  all-round  performance  rather  than  for  a  par- 
ticular condition. 

In  seaplane  work  a  problem  arises  which  is  not  found 
in  the  land  airplanes.     This  problem  is  that  of  obtaining 


AI.K01M.AM.   AM)   SKAIM.ANK    K.\<;  I  NKI .]{  1  \  i . 


tlir  crc.-itcst  reserve  of  |m»i  r  to  n\  i  rcoiue  the  resistance 
of  tin-  Hn.-it  system,  because  it  is  desirable  to  have  the 
_TC  at.  st  possible  reserve  ti>  accelerate  rapidly  on  the 
watrr.  so  that  the  ^i-t  away  may  In-  made  in  rough  water 
with  the  greatest  possible  rapidity,  thereby  reducing  the 
uinislimciit  which  tin-  sraplan.-  suffers  under  siu-li  <-on 
litions.  I-'or  a  licavily  loaded  seaplane  this  consideration 
nay  IK-  of  \  ital  importance. 

Efficiency  of  the  Propeller 

It  must  he  understood  that   the  efficiency  of  an  airplane 

propeller    is    absolutely    depeiident    upon    its    speed    of    ad- 

vanee    through    the    air.    as    is    also    the    power    which    the 

impeller    alisorhs    in    flight,    the    result    being    that    CM-II 

liou^li    the    full    throttle    is    used    the   engine   cannot    make 

its   full    revolutions   until  a  good   flying  speed   is   attain., I. 

with  the  consequence  that   full  power  of  the  motor  cannot 

:ie    realized    until    flying   speed    is    attained. 

The  efficiency  of  a  propeller  is  dependent  upon  n  func- 
tion of  the  velocity  and  the  number  of  revolutions  and 
tin  diameter  of  the  propeller  represented  by  the  frac- 

y 
ion  -          The    efficiency,    the    torque   and    the    thrust,    the 

lorscpower  absorbed  and  the  horsepower  delivered  are 
'unctions  of  this  quantity,  in  which  velocity,  the  number 
>f  revolutions  and  the  diameter  must  be  expressed  in 
lie  same  units. 

'flu  influence  of  this  factor  is  indicated  on  the  pro- 
icller  ellicii  in -\  curve  based  on  the  values  of  the  fraction 

.    When   this   fraction  equals  0.2  the  efficiency  of  the 

ND 

impeller  indicated  in  the  example  is  only  37.5  per  cent. 
The  maximum  efficiency  is  attained  when  the  value  of 
his  fraction  is  0.59.  the  maximum  efficiency  indicated 
n  this  case  being  73.2  per  cent. 

In  the  example  chosen  I  have  used  a  Durand  propeller 
the  characteristics  of  which  have  been  determined 
>v  wind  tunnel  tests,  as  reported  in  report  No.  H  of  the 
.irocei  diiins  of  the  National  Advisory  Committee  for 
Veroimutics  —  101-1. 

To  derive  the  dimensions  for  this  propeller  I  have 
issuiued  that  it  is  desired  to  attain  the  best  results  at  80 
niles  per  hr.  with  a  I.ilk-rty  engine  operating  at  1600 
•.p.m.  and  developing  380  b.h.p..  as  shown  by  the  motor 
•haractcristic.  In  Professor  Durand's  report  he  has 
idopted  KifTel's  logarithmetic  chart,  and  I  shall  now  indi- 
•ate  how  the  diameter  of  the  propeller  is  determined. 

On  the  chart  at  a  speed  of  80  miles  per  hr.  erect 
in  ordinate  equal  to  380  h.p.  taken  from  the  scale 
>n  the  left  side  of  the  chart.  From  the  top  of  this 
irdinati  next  draw  an  oblique  line  parallel  to  the  line 
ndicatini;  the  speed,  and  draw  this  line  of  such  a  length 
nd  in  such  a  direction  ns  to  represent  IfiOO  r.p.m.  on  the 
scale  starting  with  the  origin  at  12OO  r.p.m.  From 
:he  extremity  of  this  line  m  \t  draw  a  line  parallel  to  the 
ting  the  diameter  scale,  and  taking  the  distance 
:rom  this  point  to  its  intersection  with  the  propeller 
•haracteristic  for  the  propeller  No.  N  we  find  that  this 
in.-  intersects  at  the  point  ().  Transferring  the  length 
nf  this  line  to  tin  diameter  scale  and  measuring  in  the 
firection  in  which  it  is  necessary  to  draw  this  line  to 
anake  it  intersect  with  the  propeller's  characteristic,  we 


find  that  the  proper  dinmeter  to  use  is  (1. 4  ft.,  in.li,  ,lin- 
an  efficiency  of  <;•.'  )..  r  nut  Hy  the  us,  nf  tills  ingenious 
chart  it  is  possible  to  select  a  pmp<  r  diameter  for  a 
given  set  ul  conditions  by  a  simple  graphical  solution. 

The  diameter  now  Ik-ing  determined,  it  is  next  neces- 
sary to  determine  the  perform. nice  of  the  combined 
engine  and  propeller,  and  this  is  done  as  follows:  On  i 
transparent  sheet  of  paper  or  tracing  cloth  a  base 
line  is  drawn  and.  from  any  convenient  point  on  this 
line,  another  is  now  drawn  parallel  to  the  scale  of  pro 
peller  diameters  and  a  distance  is  laid  off  representing 
the  diameter  of  the  propeller  on  that  scale.  I' mm  the 
extremity  of  this  line  a  new  line  is  drawn  parallel  to  the 


Chart   for   Determining  the   Performance  of  a   IJIierty    Knjrfne 
am)  a  Durand   No.  H   Pro|>rllrr 

scale  of  revolutions  per  minute,  and  on  this  line  is  indi- 
cated the  revolutions  per  minute  of  the  powerplant. 
using  the  scale  of  r.p.m.  for  this  purpose.  From  each 
point  representing  the  different  revolutions  vertical  or 
din  iles  arc  now  drawn,  representing,  according  to  tin- 
horsepower  scale,  the  brake  horsepower  dc\eln|M-d  by  the 
engine  at  these  revolutions,  and  through  the  points  so 
determined  a  motor  b.h.p.  curve  is  drawn. 

Ni\t  place  this  diagram  on  top  of  the  logarithmetic 
diagram  of  the  propeller,  placing  the  origin  on  the  base 
IIIK  /  on  the  base  line  of  the  logarithinetie  diagram 
with  the  point  .1  at  the  s|x-ed  at  which  it  is  desired  to 
determine  the  brake  horsepower  available.  The  pro 
peller  efficiency,  and  from  the  latter  the  e.h.p.  available, 
can  now  Ik-  determined. 

This  construction  is  based  on  the  fact  that  the  hone- 
power    absorbed    by    the    propeller    and    the    horsepower 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


delivered  by  the  engine  must  agree.  Thus,  for  example, 
placing  the  point  A  at  a  speed  of  30  miles  per  hr.  it  is 
found  that  the  brake  horsepower  curve  of  the  diagram 
intersects  the  propeller  characteristic  and  the  engine 
characteristic  at  a  point  B,  indicating  that  the  engine 
will  make  1500  r.p.m.  and  develop  355  b.h.p.  at  this  speed 
of  advance. 

By  drawing  a  vertical  line  through  this  point  of  inter- 
section of  the  two  curves  to  the  dotted  characteristic  of 
the  same  propeller,  the  e.h.p.  developed  by  the  propeller 
may  be  determined.  This  can  also  be  determined  by 
measuring  the  distance  on  the  vertical  line  between  the 
full  line  and  dotted  line  representing  the  propeller  char- 
acteristics. By  transferring  the  length  of  this  line  to 
the  scale  for  efficiency,  the  propeller  efficiency  can  be 
determined. 

In  this  manner  the  brake  horsepower  available  and  the 
e.h.p.  available  have  been  determined  and  are  shown  on 
the  horsepower  curves  on  page  3.  It  will  be  seen  that  at 
30  miles  per  hr.  the  engine  can  only  turn  the  propeller  at 
1500  r.p.m.,  developing  555  b.h.p.  Also,  that  at  this 
speed  the  efficiency  is  only  35  per  cent  and  only  12-1  e.h.p. 
is  available,  although  the  engine  is  developing  355  b.h.p. 

Determining  Plane  Performance 

Having  now  determined  the  e.h.p.  available,  we  are 
ready  to  determine  the  performance  of  the  aeroplane.  It 
will  be  noted  that  the  lowest  speed  indicated  in  power 
flight  is  58.5  miles  per  hr.  Thus  these  two  points  of  per- 
formance are  determined. 

The  climbing  power  of  the  aeroplane  with  full  power 
is  determined  by  taking  the  difference  of  e.h.p.  required 
and  e.h.p.  available  at  the  particular  speed  at  which  the 
airplane  is  flown  in  the  climb.  This  difference  is  greatest 
at  the  speed  of  73  miles  per  hr.  The  climb  is  determined 
from  the  reserve  e.h.p.  available,  which  in  this  case  is 
76.  Multiplying  this  e.h.p.  by  33,000  and  dividing  by  the 
weight  of  the  airplane,  assumed  in  the  example  to  be 
6500  lb.,  it  is  found  that  the  initial  climb  should  be  386 
ft.  per  min. 

Further  inspection  of  the  curves  shows  that  the  mini- 
mum horsepower  is  required  at  a  speed  of  62  miles  per 
hr.  -It  is  at  this  speed  that  the  airplanes  should  be 
flown  to  get  the  greatest  endurance.  If,  however,  it  is 
desired  to  get  the  greatest  range,  the  most  favorable 
speed  will  be  indicated  by  drawing  a  tangent  from  the 
origin  to  the  e.h.p.  required  curve,  as  at  this  point  the 
most  favorable  ratio  is  attained  between  velocity  and 
horsepower  required. 

In  the  example  this  speed  is  found  to  be  higher  than 
the  speed  for  minimum  power  and  is  about  73  miles  per 
hr.  It  will  b«;  noted  that  the  tangent  to  the  curve  sub- 
stantially conforms  to  the  curve  over  the  range  of  speed 
from  70  to  76  miles  per  hr.  If  the  endeavor  is  being 
made  to  cover  the  greatest  possible  distance,  it  would 
be  desirable  to  select  the  higher  of  these  two  speeds,  for 
the  reason  that  at  the  higher  speed  the  controls  would  be 
more  effective;  the  flight  would  be  steadier  and  would  be 
accomplished  in  a  shorter  time. 

As  the  aeroplane  proceeds  its  weight  will  be  reduced 
because  of  the  consumption  of  fuel,  and  with  a  plane 
of  heavy  carrying  capacity  this  reduction  of  fuel  at  the 


end  of  a  long  flight  will  appreciably  reduce  the  load  and 
thereby  decrease  the  horsepower  required  for  flight. 

In  the  example  chosen,  I  have  indicated  the  horsepower 
required  when  all  the  fuel  is  used  up,  assuming  a  weight 
at  this  time  of  1500  lb.  In  this  condition  the  most 
efficient  speed  will  again  be  indicated  by  a  tangent  to 
the  origin,  and  in  the  example  this  speed  is  appreciably 
lower  than  that  indicated  for  the  full  load  condition, 
being  anywhere  from  55  to  60  miles  per  hr.  At  inter- 
mediate stages  intermediate  speeds  will  be  found  the 
best  for  the  greatest  range.  This,  therefore,  indicates 
that  in  planning  a  long-distance  flight  due  account  should 
be  given  to  this  effect,  as  the  radius  of  flight  will  be  ap- 
preciably increased  if  proper  account  is  taken  of  the  in- 
fluence of  change  in  weight.  To  be  exact,  the  tangent 
should  not  be  drawn  to  the  e.h.p.  required  curve,  but  to 
a  set  of  curves  which  can  be  derived  from  these  curves 
indicating  the  fuel  consumption  at  different  speeds  and 
at  different  loads.  The  determination  of  the  fuel  con- 
sumption curves  is  a  simple  matter,  but  it  would  take 
more  time  and  space  than  I  consider  it  desirable  to  give 
in  this  paper.  I  can  state,  however,  that  the  favorable 
speeds  for  long-distance  cruising  are  not  appreciably 
affected  by  using  these  fuel  consumption  curves  in  pref- 
erence to  the  e.h.p.  required  curves. 

The  computations  made  in  deriving  the  curves  showr 
have  been  based  on  the  Liberty  engine,  using  straight 
drive.  If  it  were  possible  to  have  available  the  same 
power  with  the  geared-down  propeller,  it  would  be  pos- 
sible to  greatly  improve  the  propeller  efficiency  anc 
thereby  to  improve  the  performance  of  the  airplane  indi 
cated  in  the  example.  It  is  unfortunate  that  the  geared 
down  engine  is  not  available  for  general  use,  as  the  per 
formance  of  practically  every  plane  I  know  of  usinj 
tin's  engine  in  our  country  would  be  materially  improve( 

y 
bv  its  use.     An  inspection  of  the   -  —  efficiency  plot  wil 


make  this  clear.  I  also  consider  it  unfortunate  tha 
in  the  development  of  the  geared-down  Liberty  engine 
which  have  been  produced,  advantage  has  not  been  take] 
of  the  possibility  of  locating  the  propeller  more  centrall; 
in  relation  to  the  engine  group,  because  of  the  advantage 
which  would  be  gained  in  streamlining.  This  engine  i 
extremely  awkward  to  streamline  in  its  present  form. 

Design  of  Seaplane  Floats 

I  will  now  proceed  to  the  consideration  of  some  o 
the  elements  of  design  of  seaplane  floats.  The  require 
ments  of  seaplane  floats,  because  of  the  nature  of  thei 
use,  are  necessarily  conflicting,  and  the  best  that  can  b 
done  is  to  make  a  compromise,  bearing  these  in  mind. 

The  first  requirement  of  a  float  is  that  it  shall  be  set 
worthy.  This  requires  that  the  form  shall  be  properl 
proportioned  to  provide  good  initial  stability  and 
reserve  of  buoyancy.  This  is  necessary  to  obtain  a  re 
serve  of  stability,  as  the  seaplane  must  float  withoJ 
capsizing  in  a  sea-way  and  in  strong  winds.  This  r 
quirement  in  itself  conflicts  with  airworthiness  ad 
lightness  and  with  the  adoption  of  the  best  streamliJ 
form,  which  otherwise  would  be,  in  general,  a  form  sir 
ilar  to  a  dirigible.  It  must  be  strong,  but  this  natural! 
conflicts  with  lightness.  It  must  also  have  good  plal 


AKKOl'I.ANK   AM)  SKAIM.ANK    KN( .  I  M  .KM  I  \  i , 


nil   qualities.   .Hid   tlii-.    reipiirem.nl    conflicts    with    str.   un 
nc    form.      Airworthiness    requires    that    it    should    have 
ir    iiiiniiiiiini    resistance    and    interfere    ill    tin-    I 
hli-  decree   with   the  otlliT  characlerist  ics  of  the  seaplane. 

In  order  to  dcu-lop  tin-  best  form  of  hull,  tin  Vi\\ 
)r]>;irtinriit  began  experinn  ills  .it  tin-  Washington  nmili  1 
•isin  late  in  lull.  These  experiments  wen  initiated  by 
apt.  W.  I.  Chambers.  I  .  S.  V.  with  a  \  ii  -w  to  tin- 
si-  of  hydroplane  IHadi-s.  such  as  had  been  used  li\ 
orlaiiini.  anil  to  improving  tin  |«)aninir  <|imlitics  of  the 
ii-n  existing  types  of  floats.  At  that  time  the  most  sue 
iful  float  was  that  eonstriieted  by  (ileiin  II.  Curtiss. 
i\  iiiiT  a  simple  l>o\  seel  ion  and  a  slid  form  profile.  At 
le  same  time  Burgess  I,.,,]  developril  twin  floats  having 
single  step,  which  had  also  pnn-  -fid. 

One  of  the  earliest  experiments  at  tin-  model  liasin  was 
i  attempt  to  reduce  the  welted  surface  to  a  minimum  by 
ic  use  of  a  semi-circular  section  in  the  form  of  a  half- 
ilind.r  whose  ends  were  pointed  like  a  projectile  to 
•diice  the  air  and  water  resistance.  It  was  fortunate 
lat  this  model  was  tried  ainonir  the  first,  for  its  trials 

once  showed  up  a  factor  which  later  was  discovered 
)  lie  of  the  greatest  importance,  this  factor  bcinir  suction, 
n-  to  downward  curxcd  surfaces  when  exposed  to  tin' 
intact  of  water  at  high  speeds.  It  was  nt  once  realized 
lat  in  the  test  of  the  floats  due  allowance  sho  lid  br 
ade  to  repns.nl  tin  change  in  load  carried  by  the  float 
s  the  speed  of  the  seaplane  increased  and  the  lift  of 
it-  wmijs  hccamc  an  important  factor,  and  all  runs  at 
ie  model  I'asin  had  In'en  made  taking  account  of  this  and 
•tcrminini;  for  each  particular  speed  the  "  corresponding; 
splaccmcnt  "  of  the  float.  This  was  originally  done  by 
mnterwcighting  the  float  so  that  the  weight  resting  on 
<•  water  represented  that  which  would  he  the  case  fak- 
ir into  account  the  auxiliary  lifting  power  of  the  wings, 
i  the  latest  form  of  apparatus  for  testing  at  tile  basin 
lis  compensation  is  automatically  made  by  the  use  of 
i  inclined  vane  submerged  in  the  model  basin,  which, 
v  mi-ails  of  a  system  of  pulleys,  exerts  a  lifting  power 
Inch  is  proportional  to  the  lifting  power  of  the  wiims 
:  the  speed  at  which  the  test  is  run. 

In   the   tests   with  the  semi-cylindrical   model  above  re- 
•rred  to.  it  was  found,  as  anticipated,  that  the  resistance 
t    low    and   moderate    spuds    was    less   than   that   cxperi- 
>ith  other  models,  lint   as  one  half  of  the  speed  for 
away  was  approached,  and  therefore  the  float  car- 
ed only    thr.  i    quarters  of  the  original  load,  it  was  found 
mt    the    resistance    of   this    model    instead    of   decreasing. 
icreased:    and    that    the    model,    instead    of    pinning,    as 
as  expected,   settled   into  the  water  and.  finally,  at   the 
et-away  speed,  with  no  weight  being  carried  by  the  float 
ut  the  float  just  in  contact  with  the  water,  the  influence 
ion  was  so  great  that  this  model,  instead  of  skim- 
ing   the    surface,    proceeded    to   envelope    itself    in    water 
a  drawn  down  so  sharply  by   suction  that   its  deck 
M  flush   with   the  surface  of  the  water  in  the  tank  and 
h.ets   of   spray    were    lifted   clear   of    the   surface 
f  the   mod-.1!  basin. 

A»  the  work  progressed  the  models  of  every  known 
uccessful  type  of  float  were  tried  in  the  model  basin. 
nd  data  were  collected  as  to  the  performance  of  these 
lodclv  At  the  same  time  many  exjx-rimental  model* 


were  tried,  and  when  these  showid  imprint  im  ir 
existing  types,  full  si/id  floats  »,  r.  eonstriieted  and  tried 
out  in  actual  flight.  I' mm  these  trials  it  was  found  that 
tin  i •oiiditions  indie.it>  d  in  tin  model  li.isin  wen  duplicated 
ill  practice  with  full  size,  and  it  uas  set  n  that  the  model 
I  asin  tests  fori!  ins  of  predicting  the  pi  rtorui  un  •• 

of    full    sl/.ei|    |(. 

The    steps    of    the    Hurgess    floats    were    ventilati  d.    and 
an   investigation  of   this   feature   showed   the   value   < 
tilation   for  the  step  type   floats   then   in   use. 

All    sorts   of   bow    forms   were   tried    and    were   shown    to 
•  r\     little    influence    on    performance.      The    use    of 
one.  two.  three  and   four   steps   wns   tried,   and   the   indn  i 
dons  were  that   there   \\.-is   little,  if  any.  advantage  to  IM- 
gained  by  the  use  of  more  than  two. 

The  introduction  of  the  V  bottom  showed  promise  of 
improienn  nt.  but  it  was  early  found  that  a  V-lftittom 
at  the  how  was  invariably  associated  with  large  i|iianti- 
:  spray  which  would  flow  over  the  planes,  and  also. 
a  cross  wind  would  make  the  navigation  of  the  senpl-ines 
very  uncomfortable.  It  was  found  by  making  the  lines 
hollow  at  the  bow  that  this  spray  could  he  held  down  close 
to  the  wait  r.  and  ill  some  later  designs  this  hollowinss 
was  also  introduced  nt  the  step,  apparently  with  tune 
tieial  results.  After  much  experimenting  it  finally  IM- 
.-.ime  apparent  that  the  best  form  of  hull  wns  that  em 
lodying  the  single  veiitilnted  step,  in  which  the  after 
bottom  rose  at  an  angle  of  approximately  H  deg.  to  the 
bottom  just  forward  of  the  step.  The  reasons  for  this 
ore  about  as  follows:  With  this  type  of  float  sufficient  buoy- 
ancy can  IM-  provided  abaft  the  step  to  eliminate  the  in  c.  s 
sity  of  tail  floats  for  stability.  It  was  also  found  that  by 
ventilating  the  step  the  water  flowing  under  the  forward 
bottom  flowed  over  the  step  in  the  form  of  an  im.rt.d 
waterfall  and  that  the  contact  of  this  inverted  stri  am  moved 
further  aft  as  the  speed  increased  and  i:  in  rilh  paused 


102030406060708090  100110120130140 
Seaplane   hortepower  currm  afloat   and   flylnit. 


258 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


clear  of  the  tail  of  the  float  just  before  planing  was  at- 
tained. At  this  point  maximum  resistance  was  encount- 
ered. After  this  point  was  passed  the  float  proceeded  to 
plane  on  the  forward  step,  and  because  of  the  raised 
position  of  the  tail  of  the  float,  it  was  then  possible  to  vary 
the  trim  of  the  plane  and  change  the  angle  of  attack  with- 
out again  bringing  the  tail  of  the  float  into  the  water. 
Then  progressively  as  the  speed  increased  to  flying  speed 
the  planing  power  of  the  portion  forward  of  the  step  in- 
creased rapidly  and  the  amount  of  wetted  surface  exposed 
to  the  action  of  the  water  was  rapidly  reduced,  and  the 
resistance  of  the  float  decreased,  until  finally  at  the  get 
away  the  water  resistance  of  the  float  was  eliminated. 

The  best  results  are  obtained  where  the  bottom  of  the 
float  just  forward  of  the  step  is  substantially  parallel  to 
the  axis  of  the  seaplane.  This  portion  of  the  bottom 
should  have  no  curvature  for  a  distance  of  several  feet 
forward  of  the  step. 

Attempts  were  made  to  curve  up  the  portion  abaft  the 
step  with  a  view  to  producing  a  better  streamline  form 
for  the  hull,  but  this  curvature  was  invariably  found  to 
produce  suction,  retard  planing,  and  in  many  cases  to 
augment  the  resistance  of  the  float  to  such  a  degree  as  to 
require  an  excessive  reserve  of  horsepower  in  order  to 
get  away.  There  was  one  case  where  a  flying  boat  was 
built  with  very  moderate  curvature  abaft  the  step,  but 
on  account  of  this  curvature  in  the  tail  was  unable  to 
leave  the  water  with  a  single  passenger.  Even  though  it 
could  get  up  to  a  speed  where  the  step  itself  was  clear 
of  the  water,  the  tail  would  still  drag  and  could  not  be 
drawn  out  of  the  water.  By  slightly  modifying  the  tail 
of  the  float  so  that  the  lines  abaft  the  step  were  straight, 
this  same  flying  boat  with  the  same  powerplant  was  able 
to  get  off  the  water  with  a  pilot  and  passenger. 

One  of  the  earliest  floats  tried  at  the  model  basin  and 
built  in  full  size  was  a  twin  float  having  a  sharp  V-bottom. 
The  lines  of  this  float  conformed  to  the  lines  of  a  success- 
ful gunboat,  and  it  was  very  pretty  and  clean  in  its  action, 
but  due  to  the  influence  of  the  curvature  of  the  buttock 
lines  at  the  stern,  suction  was  present  in  this  model  and 
an  airplane  fitted  with  these  floats,  although  able  to  get 
away  with  a  pilot,  was  unable  to  get  away  with  a  pilot 
and  passenger,  there  being  insufficient  reserve  power  to 
get  over  the  hump. 

Until  very  recently  it  was  considered  that  so  many 
inches  of  beam  were  required  for  every  100  Ib.  of  weight 
carried  by  the  float  in  order  to  attain  planing,  and  this 
criterion  has  led  to  the  adoption  of  the  great  beam  found 
in  the  F-5  and  H-16  and  HS-2  models.  But  experiments 
with  floats  suited  to  carry  1000  Ib.  each  indicated  that 
this  model  was  remarkably  satisfactory.  The  attempt 
was  therefore  made  to  enlarge  this  model  in  geometrical 
proportion  to  a  2000-lb.  float,  and  the  model  basin  results 
indicated  that  this  could  be  satisfactorily  done.  Another 
model  was  made  of  a  2000-lb.  float  and  behaved  satis- 
factorily. This  same  model  was  expanded  to  a  6000-lb. 
float,  which  behaved  even  better  than  the  original.  The 
lines  of  the  N-9  float,  which  has  proved  successful  in  our 
training  program,  were  developed  from  the  original 
1000-lb.  float,  although  this  float  had  less  beam  than  the 
original  full-size  float  which  was  unsuccessful.  As  a  re- 
sult of  these  trials,  I  now  consider  it  to  be  conclusively 


established  that  once  a  satisfactory  float  is  developed  fol 
carrying  a  definite  load  under  given  conditions,  the  same 
design  can  be  used  for  larger  loads  by  merely  expanding 
the  original  lines  in  the  ratio  of  the  cube  root  of  the 
displacement  ratios. 

In  the  design  of  the  float  for  the  NC-1  this  principle 
was  used  and  the  model  tested  in  the  model  basin,  aH 
though  only  one-twelfth  full  size,  gave  data  which  indi- 
cated satisfactory  performance.  These  data  have  been 
closely  verified  by  the  actual  performance  of  the  NC-lj 
though  many  designers  were  skeptical  that  this  floaj 
could  handle  its  load  on  so  narrow  a  beam.  This  is  nfl 
greater  than  that  used  in  the  F-5  ;  the  F-5  carries  a  load 
of  only  13,000  as  against  over  22,000  Ib.  carried  bj| 
the  NC-1. 

Attention  is  now  invited  to  a  series  of  curves  showing 
the  results  of  model  basin  tests  on  a  number  of  different 
models. 

Results  of  Model  Basin  Tests  Compared 
The  dimensions  of  the'  floats  and  the  seaplanes  thej 
represented  were  so  different  that  to  get  a  comparison 
it  has  been  necessary  to  plot  these  results  on  non-diuieni 
sional  scales.  It  will  therefore  be  noted  that  the  disj 
placement  of  the  hull  is  plotted  as  a  per  cent  of  tha 
total  displacement  based  on  a  per  cent  of  the  get-awal 
speed.  The  resistance  of  these  floats  is  indicated  by  9 


tAPERIMENTAL  MODEL    BASIN 

AIRPLANE  FLOAT  TESTS 
MODEL   NO.      FOR       -NAME 

H-12 

20,55  AA.D. 

20SO  H-l« 

2<*1-A  K-C-I 

2081-B 

2081-C 


30  40  50  60  70 

PER  CENT  OF  GETAWAY  SPEED 


Results  of  tests  at  model  basin  on  a  number  of  seaplane  floats. 

plot  of  the  ratio  of  the  displacement  to  the  resistance! 
also,  based  on  the  per  cent  of  the  get-away  speed. 

Based  on  the  plot  of  model  No.  2022,  which  is  that  o$ 
a  successful  H-12  boat,  I  have  plotted  the  resistance  and 
the  horsepower  required  to  overcome  this   resistance   for 
the  sample  seaplane,  the  horsepower  curves  of  which  I 
have  already  explained,  and  I  shall  return  to  those  plots 
in  a  few  minutes.      Before  doing  so,  however,  I  wish   l<> 
invite  your  attention  to  the  plots  of  models  Nos.  2081-^ 
2081-B   and   208 1-C.     You   will   note  that  the   resistanc 
of   No.   2081-A  was   nearly   one-quarter   of  the   displace 
ment    at   40    per   cent   of   the    get-away    speed ;    that    th 
resistance  of  No.  2081-B  was  reduced  to  nearly  one-fift 
of  the  displacement  at  about  47  per  cent  of  the  get-awajj 
speed,  and  the  resistance  of  No.  208 1-C  was  between  oiic- 
fifth  and  one-sixth  of  the  displacement  at  about   52   pel 
cent  of  the  get-away  speed.     Also,  the  displacement  il 
the  latter  case  is  less  than  in  the  preceding  cases. 


AKKOIM.ANK   AM)  SKAIM.ANK   KMJ  I  \  KKI{  1  \  ( . 


•J.V.i 


Tills     change      was      brought      aliout      as      follows:      The 
original    form   of   float    had    two   -I.  ps.    with   curvature   in 
Hi.    nii.ldlr  step  and  a  rank  tip-curvature  in  tin-  rear  step. 
So.    -.'iiM    15    represents    this    model    with    tin-    rear    step 
straightened,    anil    No.    -.'I  IS  I   ('    represents    this    Mnat    with 
straight   lines   for  tin-  liottom   ahaft   the   tirsl    st,  p.       It   will 
rraililr    In-    si-i-n    th.it    tin-    first    modification    was    an    im- 
provriurnt    oicr   tin-   original,   ami    tin-   s.-conil   ino<lifiratioii 
was    a    still    greater    improvement.      Thrsr    modi  Is    rcprc 
si-nt   tin-   model  of  the   NC-I.  and   there   is  no  doubt    in   my 
mind    that    if   tin-   original    inodi-1    had    heen    iisi-d    this   sea- 
plane   could    not    have    pit    oil'    the    water.       Further,    the 
influence    lit    the    curved    portion    at    the    tail    of   the   float 
would   have  been  so  great   as  to  cause  the  machine  to  squat 
so   liailly    that   the   tail    surfaces   would   have   heen   caught 
in   thr   stream   of   water   rising   from  the  tail   of  the   float. 
Let    us    now     return    to    the    horsepower    curves.      It    will 
he  noted  that  the  resistance  of  this  seaplane  float  reaches 
a   maximum   at    a   speed   of   •„'<)   miles   per   hr..   which   speed 
corresponds    to    n    point    at    which    planing    lie-ins,    and 
there    is    a    secondary    hum))    at    a    speed    of     to    miles 
per   hr.      The  get-away   speed   is  assumed   as   lix!   miles   j)er 
hr.      The    horsepower    curve    has    been    directly    derived 
from  the  resistance  of  the  float,  and  this  horsepower  must 
he    compounded    with    that    of    the    airplane    progressing 
through   the  air.     The  horsepower  required   for  this  pur- 
pose is  determined   by  taking  the  horsepower  of  the  air- 
plane at  ii-,'  miles  per  hr..  which  in  this  ease  is  150  e.h.p., 
and   noting  that  the  horsepower  for  the  wings  and   head 
resistance  is  proportional  to  the  cube  of  the  speed.     We 
thus  derive   the  curve  of  the  total  air  e.h.p.  required   for 
the  seaplani  .  which  must   he  compounded  with  the  horse- 
power   required    for    the    float,    thus    giving    »s    a    total 
horsepower  curve  for  the  seaplane  for  speeds  below  the 
get-away  speed,  that  is.  while  still  in  the  water. 

l-'rom  an  inspection  of  the  horsepower  curves,  it  will  be 
set  n  that  the  maximum  horsepower  for  the  float  is  re- 
quired at  a  .speed  of  about  •„':!  miles  per  hr.,  and  that  this, 
compounded  with  the  horsepower  due  to  air  resistance, 
requires  88  h.p.  at  this  speed. 

The  horsepower  for  planing  is  very  little  exceeded  by 
the  horsepower  available,  so  that  it  would  take  a  rela- 
tively long  time  to  pass  through  the  planing  condition; 
but.  after  this  point  is  passed,  the  seaplane  should  accel- 
erate rapidly  because  the  reserve  of  horsepower  available 
rapidly  increases  up  to  the  get-away  speed. 

There  is  a  secondary  hump  in  the  horsepower  curve  at 
60  miles  per  hr.  just  he  fore  the  get  away  in  attained,  but 
this  secondary  hump  is  of  little  importance  as  there  is 
an  ample  reserve  of  horsepower  at  this  point. 

As  a  matter  of  interest,  I  have  investigated  the  im- 
provement in  performance  which  could  bt  expected  if 
a  geared-down  engine  were  used,  assuming  a  ratio  of  0.6; 
that  is.  the  propeller  turning  at  0.6  of  the  revolutions  of 
the  engine.  With  this  gear  ratio  a  propeller  IS  ft.  in 
diameter  is  indicated.  Such  a  propeller  at  a  speed  of  80 
miles  IXT  hr.  would  show  an  efficiency  of  73  per  cent  as 
against  6W  per  cent  for  the  »-ft.  diameter  propeller. 
This  gain  of  I  per  cent  at  HO  miles  per  hr.  would  increase 
the  climb  by  more  than  1 1  per  cent.  It  would  have  little 
effect  on  the  speed,  as  the  horsepower  curve  is  very  steep 
in  this  region.  The  improvement  in  efficiency  at  20  miles 


per  hr.,  although  only  6  per  cent  would  mean  an  met 

of  -..'00  per  cent  in  the  r.s.rv,  of  horsepower  to  get  over 
the  hump  in  the  horsepower  curve  at  that  speed.  You 
will  therefore  see  why  in  naval  work  the  use  of  the 
geared  down  propeller  oll'crs  considerable  advantage. 
The  siilstitution  of  the  gcared-down  Liberty  for  the 
straight  drive  Liberty  engines  in  th.  I  .1  changes  the  top 
speed  of  this  seaplane  from  '.Ml  to  loo  nnli  s  p,  r  hr.  and 
makes  the  get  away  of  this  seaplane  certain  and  rapid 
under  all  conditions,  whereas  the  straight-drive  propellers 
were  only  able  to  get  this  boat  with  great  difficulty  in  a 
calm. 

The   V- Bottom   Versus  the   Flat 

I. \periments  have  recently  heen  made  at  the  model  basin 
on  a  series  of  models  having  different  angles  of  V-bottom 
from  the  flat  bottom  up  to  a  20-deg.  V,  and  it  is  found 
that  from  a  resistance  point  of  view  there  is  very  little 
difference  in  the  performance  of  the  four  models  tried. 
So  far  as  any  advantage  is  shown,  the  deep-angle  V 
has  slightly  the  l>est  of  the  argument.  From  a  service 
point  of  view  the  deep  V-bottom  has  many  advantages; 
among  them  its  remarkable  shock-absorbing  properties 
in  taking  care  of  bad  landings,  or  in  getting  away  and 
landing  on  a  rough  sea.  The  V-bottom  also  permit- 
landing  across  the  wind  without  serious  retardation  and 
without  danger  of  capsizing  sideways.  This  type  of  hull 
appears  to  absorb  the  shock  by  penetration  and  reduces 
the  loads  imposed  on  the  bottom  planking  and  on  the 
framing  supporting  this.  Due  to  this  feature  there  is 
no  need  of  carrying  shock  absorbers  between  the  floats 
and  the  rest  of  the  plane  structure,  and  the  lightest 
possible  construction  can  Iw  adopted. 

In  the  longitudinal  system  of  support  the  inner  ply 
of  planking  is  run  athwartship  and  thereby  constitutes 
a  continuous  system  of  ribs.  This  system  is  further 
reinforced  by  the  outer  planking  run  45  deg.  to  the  keel, 
which  also  acts  as  a  continuous  system  of  ribs,  and  these 
two  systems  transmit  the  water  pressure  as  a  distributed 
loading  to  the  longitudinal  members,  which  do  not  have 
their  strength  robbed  by  a  series  of  notches.  The  lon- 
gitudinals are  arranged  so  that  they  collect  the  dis- 
tributed load  and  concentrate  it  at  points  of  support  in 
athwartship  bulkheads  and  these  bulkheads  in  turn  dis 
tribute  the  load  to  the  keel,  to  the  chine  stringers,  and  to 
the  deck  planking.  The  keel  itself  is  usually  associated 
with  a  center  longitudinal  truss.  Through  these  mem- 
bers the  load  is  finally  distributed  to  struts  or  directly 
to  the  wing  structure. 

On  a  large  scale  this  system  is  adopted  in  the  construc- 
tion of  the  hull  of  the  NCI  which,  although  it  embodies 
other  features  than  those  necessary  to  support  the  bot- 
tom planking,  weighs  only  £600  Ib.  while  it  carries  a 
load  of  -J-MI.IH  Ib.  This  hull  has  demonstrated  ample 
strength  in  landing  on  and  getting  off  an  8-ft.  cross  sea 
in  practically  dead  air,  where  the  landing  and  get  away 
were  both  made  under  the  hardest  conditions. 

A  controversy  has  existed  for  years  as  to  the  merits 
of  the  single  float  as  compared  with  the  twin  float,  but. 
based  on  the  experience  of  our  Navy  with  examples  oi 
both  types,  I  believe  that  the  central  float  with  wing  tip 
balancing  floats  is  decidedly  the  better  arrangement.  In 


'260 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


the  central  float  system  the  loads  can  be  concentrated  on 
the  point  of  support,  whereas  in  the  twin-float  system 
the  loads  are  usually  concentrated  in  the  center  of  the 
span  and  the  wing  structure  has  to  be  utilized  to  gain 
the  necessary  stiffness  and  necessarily  has  to  be  made 
heavier.  In  the  center-float  type  if  a  single  propeller  is 
used  it  is  located  above  the  float  and  protected  from  the 
water,  whereas  in  the  twin-float  type  such  propeller  neces- 
sarily swings  over  the  gap  between  the  floats,  which 
subjects  it  to  punishment  by  spray  and  broken  water. 
In  landing  a  twin-float  seaplane,  unless  botli  floats  arrive 
at  the  same  time,  the  second  float  invariably  strikes 
harder  than  the  first,  being  slammed  down  on  the  water. 


Due  to  the  greater  lateral  stiffness  of  the  twin-float  sys- 
tem, when  getting  off  rough  water  the  seaplane  is  forced 
to  conform  in  its  attitude  to  the  form  of  the  surface 
and  wracks  and  lurches  violently  sideways  unless  going 
directly  across  the  crest  of  the  sea.  In  maneuvering  in 
the  air,  also,  the  separation  of  the  twin  floats  adds  con- 
siderably to  the  inertia  about  the  longitudinal  axis  and 
makes  the  action  of  the  ailerons  less  effective.  With  twin 
floats,  when  taxi-ing  across  a  strong  side  wind  the  lee 
float  must  have  at  least  100  per  cent  reserve  buoyancy 
and  this  leads  to  greater  weight  than  is  necessary  witli 
the  single  center-float  providing  the  same  stability. 


Appendix 

V 

3 

Kill', 

The  tables  appended  give  the  calculations  for  the  per- 

10 

20 

1,000 
8,000 

O.Hi 
1.28 

formance   curves  of  a   seaplane   with   a   biplane   arrange- 

30 

27,000 

4.32 

ment  of  R.  A.   F.   6   wings  and  a   head   resistance  of  20 

40 

64,000 

10.34 

sq.  ft.     In  these  calculations  the  following  formulas  were 

50 

125,000 

20.00 

usod  : 

60 

216,000 

34.60 

70 

343,000 

55.00 

80 

572,000 

82.00 

K                W                  TV 

T  =  W  4-  -7-^  I'-  =  -r—  ,  EH~P  —  -  

90 

729,000 

110.50 

/i                1\.  S                   375 

100 

1,000,000 

KiO.OO 

120 

1,728,000 

270.00 

W  —  Weight  in  pounds 
T  =  Thrust   in   pounds 
V  =  Velocity  in  miles  per  hour 
8  =  Wing  surface  in  square  feet 
*^.  =  Drift  factor  for  biplane  arrangement 
KU  —  Lift  factor  for  biplane  arrangement 


EHP, 


WAV-   T',   AV 


% 


=  6500      l^     =M4g 


/W, 

\  «              /  H 

^2  \ 

EHP 

(w. 

',)    =  I-3(ii 

rj  =  1.73 

T           KJS 

F* 

r           TV 

Flanes 

- 

EPIli 

r, 

EIIP,                 V, 

1,030         0.301 

21,600 

147.0         151,300 

404.0 

0 

404.0 

147.0 

234.0                 122.5 

532         0.595 

10,900 

104.5           55,700 

148.5 

2 

148.5 

104.5 

86.0                   87.0 

474         0.861 

7,550 

87.0           41,200 

110.0 

4 

110.0 

87.0 

68.5                   72.5 

516         1.085 

5,990 

77.5           40,000 

106.7 

g 

106.7 

77.5 

61.5                   64.5 

575         1.309 
618         1,512 

4,960 
4,300 

70.5           40,500 
65.7           40,600 

108.0 
108.2 

8 
10 

108.0 
108.2 

70.5 
65.7 

62.4                   58.8 
62.5                   54.8 

684         1.708 

3,800 

61.7           42,200 

112.2 

12 

112.2 

61.7 

65.0                   51.5 

833         1,848 

3,520 

59.5           49,500 

132.0 

14 

132.0 

59.5 

76.3                   49.6 

1,160         1.911 

3,400 

58.5           67,900 

181.0 

16 

181.0 

58.5 

104.6                   48.8 

K  SV3 
EIIPh  =  —  ^pp  and    is   independent   of   the   angle   of   attack. 

The  float 
and  having 

EHP  for  an  H-12  seaplane  weighing  6500  Ib. 
a  get-away  speed  of  62  miles  per  hr.  is  given 

K  S  —  0.06  and  ~ 
37o 

=  0.00016 

below    for 

varying 

percentages 

of   the    get-away    speed. 

Angle  of 

attack,  deg.    Kx 

X  10,000    K 

X  10,000 

Kl/Kx 

W 

0 

0.62 

4.3 

6.3 

6,500 

2 

0.65 

8.5 

12.2 

6,500 

4 

0.88 

12.3 

13.7 

6,500 

6 

1.20 

15.5 

12.6 

6,500 

8 

1.65 

18.7 

11.3 

6,500 

10 

2.06 

21.6 

10.5 

6,500 

12 

2.55 

24.4 

9.5 

6,500 

14 

3.30 

26.4 

7.8 

6,500 

16 

4.85 

27.3 

5.6 

6,500 

Per  cent  of 

Get-away 

Speed       r 

A<  Per  cent 

A.lb. 

A/R 

R 

RV 

EIIP 

10 

6.2 

99.00 

6,430 

20 

12.4 

95.70 

6,220 

9.80 

635 

7,880 

21.0 

30 

18.6 

91.00 

5.910 

4.90 

1,205 

22,400 

59.8 

40 

24.8 

84.00 

5,460 

4.6.5 

1,172 

29,100 

77.7 

50 

31.0 

75.00 

4,870 

5.40 

903 

27,100 

72.3 

60 

37.2 

64.00 

4,150 

6.15 

675 

25,100 

67.0 

70 

43.4 

51.00 

3,310 

6.10 

543 

23,600 

63.0 

80 

49.6 

36.00 

2,340 

5.30 

442 

21,800 

58.2 

90 

55.8 

19.00 

1,235 

4.00 

309 

17,300 

46.2 

100 

62.0 

0.00 

0 

.\KHOIM..\\K   AM)   SK.MM.ANK    ENGINEERING 


261 


I).\T\  <>\  on  i  i  KI  M    rrPBfl  "i    I  II  INC  BOAT* 


Wright.    fnll>    |,..,(l,-<l.    ll> 

fs.-flll        1.1.111.        Ml 

M.ixiiiiiiin   speed,  miles  JUT  hr. 

Miiiiniiiiii  speed,  mill--   |KT  hr 

Initinl  i-linili.  ft 

•II   span.  ft. -in 

II   length,   ft. -in 

II   height,   ft.  in 
Chord,    ft. -in.  

'  rra.    s(|.    ft 

Hull    length,   ft. -in. 

rryinj;  a   loail  of   .'l.'.Mi  ML 

\in-  .-,  I.,  i, I  ,,i 


ll>    1 

II  l', 

S.      1 

10.900 

13JOOU 

. 

,%400 

4,740 

7,740 

•M 

94 

-i 

44 

46 

47 

61  i 

i',400  to  3,000  ill   10  min. 

3,000   In    10  min. 

•i    lo   min. 

<    in    '.   min 

;  i     o  i" 

94    0  13/16 

103    9  1/4 

IM    0 

38    4  14/16 

46     11.    :• 

49    3  11/16 

68    1  i»/3i 

II     71/4 

K     *  4/8 

18    9  1/4 

6    3  4/39 

1    0  49/64 

8    0 

I.1       0 

tat 

I.U.I 

:..'.. 

34    3 

3 

II      7 

>  \t  a  speed  of  1,7   miles  |KT  hr.  with  n  load  of  .M;JI-  II.. 


The  Discussion 

CUT.  \\".  I.  CnvMiim-:  As  to  tin-  most  serviceable 
si-;i|>l:iin-  type  at  present.  I  ran  conceive  of  tin  service 
abilitv  of  the  following  general  iiutlinr:  (I)  One  middle 
Hoat  entirely  riu-loscil.  without  cockpits.  machinery  or 
carpo  capacity:  .' i  a  short  miilillc  fuselage  located  above 
the  middle  flont.  with  engine,  pusher  propeller,  cargo  space 
.•iiicl  forward  L;IIII  mount:  ( .'i  1  two  whip  fusclapcs.  forming 
supports  tor  the  tail,  a  la  Caproni,  each  with  engine 
propeller  and  rear  pun  mounts :  i  H  two  smaller 
whip  floats  for  lialancinp  ]>nrposi-s.  not  at  the  whip  tips, 
but  located  under  the  tractor  propellers  of  the  wing  fuse 
the  tail  planes  comparatively  near  the  main 
ones  and  n--'  d  so  that  they  may  he  utilized,  in  a  fixed 
position,  to  afford  inherent  stability  on  lonp  steady  tliphts 
and  yet  be  capable  of  mobility  in  response  to  any  demands 
for  quick  manciivcrinp.  While  I  do  not  suggest  any 
finality  as  to  model  or  type  of  either  powcrplant  or  rig 
of  the  plains.  I  do  not  hesitate  to  predict,  however. 
that  future  modification  ami  improvement  will  depend 
.pon  further  improvement  of  the  powcrplant  than 
on  any  other  factor.  (Ireat  improvements  in  tlii.  part 
of  the  aircraft  an  due.  and  each  decisive  step  will  result 
in  a  modification  of  airplane  types  for  each  specific  pur- 
!>,.*, 

OIIMIII     WiniiiiT:       Commander    Richardson's    figures 
for  the  performance  of  propellers  arc  based  on  tables  de- 
Tom    experiments    with   models.      The   trouble   with 
tables   ,,f   this   kind    comes    from    the    fact   that    it    is   most 
iilficult   to  determine   the  exact   value  of  each  of  the   fac- 
lors   which  play  a  part  in  the   pro|M-llcr's  efficiency.      The 
re-  made  with  several  variable  factors,  so  that  the 
measurements   secured   really   show   the   result   of   the   sum 
if  these  variables.      The  exact  value  of  each   one   is   not 
ued.      I    am   of   the   opinion    that    much   closer   cal- 
ulatioiis  .•an   IH-   had  from  a  theoretical  consideration  of 
M  lions   that   must   take  place  in  a   propeller.      Cotn- 
n.-ind.  r    Richardson    tinds    that    a    propeller    '.i.  t     ft.    in 
r.    driven    by    a    Liberty    engine,   turning   at    Minn 
r.p.m.  and  developing  :fSO  b.h.p..  in  traveling  forward  at 
niles  per  hr..  would  have  an  efficiency  of 
i'.'   p-  r  cent,  or  a   loss  of  only  SI    per  cent.      I   believe  it 
•an   !«•  show  n   that  the  loss   from   slip  alone,  without   con 
<idcring   any   of   the    other    losses,   which    also   would    be 

would  IM*  more  than  the  amount  he  has  found. 
When  the  thrust   is  known  the  slip  can  be  determined 
•asily.  because  slip  is   merely    the  acceleration   imparted 


to  a  mass  of  air  by  the  impact  of  the  profiler  I 
Slip,  therefore,  must  lie  equal  to  /'=  V  <<7*.  <"  which  /' 
is  the  velocity;  g.  gravity  or  .S2.17  ft.  per  sec.:  I,.  head  or 
pressure.  Air  at  sea  level  may  be  considered  as  weighing 
I'.nrii-  II,.  p.r  cu.  ft.  or  I :t. !•.':«  cu.  ft.  of  air  weighs  I  Ib. 
Ileiice  a  pressure  of  1  Ib.  per  sq.  ft.  would  accelerate  air 
at  sea  level  to  a  velocity  equal  to 


V  *x!W.1 7x13.1 23  ft.  per  scr. 

But  it  is  well  known  that  the  rate  of  acceleration  is  di- 
rectly proportional  to  the  force  and  inversely  proportional 
to  the  mass.  Therefor,  acceleration  will  In-  proportional 
to  the  pressure  divided  by  tin-  volume  of  air.  The  pr.-s 
sure  of  1  Ib.  per  sq.  ft.  will  accelerate  Hit  eu.  ft.  of  air 
to  a  velocity  of  1  ft.  per  sec.  or  1  cu.  ft.  of  air  to  HU  ft. 
per  sec.  The  acceleration  imparted  to  any  other  number 
..f  cubic  feet  of  air  can  be  expressed  by  the  formula 


Acceleration  = 


844  x  pressure  In  Ib.  per  *q.  ft. 
Cu.  ft.  of  air  acted  on 


The  number  of  cubic  feet  of  air  acted  on  p.  r  square 
foot  of  disk  area  of  a  propeller  is  equal  to  the  distance 
the  propeller  moves  forward  plus  the  acceleration  or  slip 
of  the  air  acted  on.  Therefore 


Slip  - 


844  x  thrust  In  Ib.  JKT  sq.  ft.  of  disk  area 


Advance  In  ft.  +  slip  in  ft. 

If  the  propeller  considered  by  Commander  Richardson 
had  an  efficiency  of  <i:i  per  cent  at  HO  miles  per  hr.  it 
would  have  a  thrust  of  1220  Ib.  Therefore  the  thrust 
would  be  17.72  Ib.  per  sq.  ft.  of  disk  area.  In  the  formula 
for  slip  just  given,  substituting  17.7-2  for  the  thrust  in 
Ib.  per  sq.  ft.  of  disk  area,  and  117.28  for  the  advance, 
,|  th.  slip  equals  Tti.'.Ki  ft.,  a  loss  of  S'.MSii  per  cent. 
It  is  therefore  evident  that  it  would  IK-  impossible  to  se- 
cure an  efficiency  of  li'.i  per  cent  with  any  pro|>cllcr  of 
!>.  >  ft.  diameter  consuming  :isn  h.p.  while  advancing  HO 
miles  per  hr.  I  have  made  a  rough  calculation  of  the 
performance  such  a  pn  pellcr  should  give,  based  upon  the 
propeller  being  considered  merely  as  airfoils  traveling 
in  a  spiral  course.  A  prop.  Ih  r  H.  I  ft.  in  diameter  work- 
ing under  the  conditions  stated  would  have  a  thrust  of 
approximately  !>.SO  Ib. ;  the  slip  would  amount  to  M.I  per 
cent  of  the  total  amount  of  air  the  projK-ller  traveled 
through,  and  the  efficiency  of  the  angle  of  advance  would 
be  80  |MT  cent.  The  total  efficiency  would  therefore  Iw 
0.65  x  0.80  or  52  per  cent. 

Commander    Richardson   uses   a   method   of  calculating 


262 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


the  rate  of  climb  of  an  aeroplane  which  seems  of  doubt- 
ful value.  He  makes  no  allowance,  so  far  as  I  can  see, 
for  the  extra  loss  in  efficiency  of  a  propeller  when  climb- 
ing. The  thrust  in  climbing  must  be  approximately  equal 
to  the  thrust  when  flying  at  the  same  speed  on  a  hori- 
zontal course  plus  the  total  weight  of  the  machine  multi- 
plied by  the  sine  of  the  angle  of  climb.  It  is  apparent 
that  if  the  machine  were  to  climb  in  a  vertical  course  the 
propeller  thrust  would  necessarily  have  to  be  equal  to  the 
entire  load  of  the  machine.  On  an  inclined  course  the 
propeller  would  have  to  bear  a  proportion  of  the  entire 
load  plus  the  thrust  necessary  to  give  the  machine  the 
desired  speed.  When  climbing,  the  propeller  efficiency  is 
especially  low  in  small-diameter  propellers,  because  on  ac- 
count of  the  extra  load  imposed,  the  slip  becomes  ex- 
cessive. 

COMMANDER  RICHARDSON: — A  great  amount  of  theo- 
retical work  has  been  done  on  propellers,  taking  it  from 
all  points  of  view,  but  in  my  opinion  none  of  these  meth- 
ods of  analysis  are  as  satisfactory  as  the  wind-tunnel 
methods,  because  even  the  theoretical  investigations  re- 
quire the  use  of  coefficients  which  must  be  developed 
from  experience  or  practice.  And  I  believe  that  when  a 
propeller  shows  59  per  cent  efficiency  in  a  wind-tunnel 
test,  where  the  quantities  can  be  actually  measured,  that 


this  is  the  real  efficiency  of  the  propeller  in  question  un- 
der the  conditions  of  the  test,  and  no  amount  of  mathe- 
matical or  theoretical  investigation  will  convince  me  to 
the  contrary.  The  airplane  horsepower  required  curve 
shows  the  horsepower  required  to  propel  the  plant  at  any 
angle  of  attack,  and  this  is  relative  to  the  air  and  re- 
gardless of  the  path  of  the  plane.  The  horsepower  avail- 
able depends  on  the  characteristics  of  the  powerplant,  in- 
cluding the  engine  and  propeller  and,  as  I  clearly  dem- 
onstrated, the  propeller  efficiency  is  a  function  of  the 
speed  of  advance  or  the  quantity  f'/ND.  The  curve  of 
horsepower  required,  therefore,  shows  at  any  particular 
speed  of  advance  of  the  airplane  the  actual  horsepower 
effectively  delivered  by  the  propeller,  and  the  difference 
between  the  power  required  to  propel  the  plane  and  the 
actual  power  available  is  available  for  lifting.  The  brake 
horsepower  required  of  course  is  much  greater,  but  in 
the  computation  of  the  horsepower  available  the  effects 
of  the  reduced  speed  in  the  climb  are  taken  care  of.  The 
propeller  chosen  for  the  example  was  selected  for  the 
purpose  of  illustration  and  not  because  it  was  the  most 
efficient  possible.  Both  Eiffel's  and  Durand's  experiments 
have  shown  that  efficiencies  as  high  as  80  per  cent  are 
entirely  possible. 


I  HAPTKK   V 


NAVY  DEPARTMENT  AEROPLANE  SPECIFICATIONS 


The  general  specification-  of  requirements  issued  by  the 
Navy  Department  for  use  in  connection  with  contracts. 
and  the  submission  to  it  of  new  and  undemoiistratcd  de- 
s  of  aeroplanes,  ire  interesting  as  indicating  broadly 
tin-  state  of  the  art  from  the  standpoint  of  this  arm  of 
the  (ioxcrmncnt.  The  s|>ccitications  are  comprehensive, 
and  give  clear  evidence  of  ability  and  knowledge  having 
been  applied  in  the  preparation  of  them. 

Although    the    requirements    which    are    summarized   be- 
low   in    ]  irue   part,   may    IM-    modified    in    the   case   of   com 
pleted    aeroplanes   available    for    demonstration,    sufficient 
information  is  essential  in  any  ex  t-nt  to  permit  reasonable 
verification  of  claims  of  performance  and  as  to  strength. 

No  new  project  will  he  encouraged  unless  it  promises 
a  marked  adx  nice  oxer  planes  in  service  or  already  under 
trial,  (in -it  consideration  will  be  given  to  possibilities 
for  immediate  manufacture,  facility  of  upkeep  and  rapid 
dismounting  of  engines,  and  reduction  of  general  dimen- 
sions. 

(icneral  arrangement  plans,  one-twelfth  or  onc-twcnty- 

fourtli   full  size,  showing  plan,  side  and  front  elevations. 

to  be  transmitted.     The  following  are  to  be  indicated: 

Over-all  dimensions,  and  principal  dimensions  of  por- 
tion- -hipped  partly  assembled; 

Gap.  chord  and  stagger. 

Positions  and  angles  relative  to  the  propeller  nr:is  for 
the  main  and  auxiliary  surfaces  and  floats; 

•ion  of  center  of  gravity  of  aeroplane  for  full  load 
and  light  load  as  defined  under  Rules  Governing  Conduct 
of  Trials; 

Position  of  center  of  buoyancy  and  corresponding  wa- 
ter line  of  the  float  sxstem  when  at  rest  on  the  water  with 
full  load: 

Portion  of  axis  of  landing  wheels  relative  to  center  of 
gravity  for  full  load; 

.ranee  of  the  pro|x-llcr:  For  tractor  tyjx-s  to  be 
shown  with  the  propeller  axis  horizontal;  for  pusher 
ty|M-s  to  IM-  shown  with  the  aeroplane  in  position  at  rest 
on  the  surface; 

Angle  of  attack  at  rest  on  the  surface  under  full  load ; 

Areas  of  main  and  auxiliary  surfaces; 

Dihedral  angle;  sweep  back;  wash-out  or  permanent 
warp,  if  any. 

The  detail  plans  called  for  are: 

Details  of  spars,  showing  full  sixe  of  the  spar  section 
in  •  icli  bay; 

-  'ion  of  aerofoil,  showing  with  dimensions  the  posi- 
tions of  the  spars  and  details  of  wing  ribs; 

Details  of  wing  .struts  and  drift   struts,  showing  full 


sise  the  central  cross-section-,  and  details  of  taper,  if 
any  ; 

I  >.  tnls  of  typical  strut  terminal  fitting  and  wing  spar 
titling,  with  anchorage  to  wing  spar  and  to  stagger,  lift 
and  landing  wires; 

Details  of  hinge  connection  between  wing  panels; 

Details  of  aileron,  elevator  and  rudder  hinges  and 
horns,  and  general  construction  plans  of  thisc  surfaces; 

Details  of  float  construction,  including  lines  and  a  state- 
ment of  reserve  buoyancy. 

The  required  assembly  plans  are  those  showing: 

The  arrangement  of  all  control  leads  and  types  of  fit- 
tings used  with  them; 

The  installation  of  compass,  instruments,  armament  or 
other  special  gear. 

Arrangement  of  wing  wiring,  including  lift  and  land- 
ing wires,  drift  and  stagger  wires,  and  tabulated  strengths; 

Landing  gear  and  shock  absorbers,  size  of  wheels,  tires. 
axles  and  struts ; 

Propeller  proposed,  including  section  and  angles  at  sta- 
tions o.l  ;>.  O..SO.  o.  r..  o.«0  and  0.90  of  radius; 

Mounting  and  general  installation  of  the  engines,  with 
oil  and  gas  tanks,  starting,  air  intake,  exhaust,  and  all 
piping  arrangement; 

Cowling  and  ventilation  arrangements  for  engine  and 
cooling  -y-tem.  giving  complete  specifications  of  radia- 
tors employed. 

These  further  data  are  asked  for: 

Detailed  tabulation  of  estimated  weights,  showing 
weights  included  in  light  load  and  full  load  with  the  cal- 
culation of  the  locution  of  the  center  of  gravity  vertically 
and  horizontally  for  each  of  these  conditions  with  refer 
ence  to  the  front  edge  of  the  lower  plane  with  the  pro- 
(M'llcr  axis  horizontal ; 

Diagram  showing  loads  on  the  principal  members  of 
the  wing  and  body  truss,  including  a  tabulation  of  the 
characteristics  of  the  principal  members,  their  loads  and 
stresses  under  the  several  conditions  specified  under  Fac- 
tors of  Safety ; 

Calculated  performance  chart,  showing  the  curve  of 
effective  horsepower  required,  the  propeller  efficiency,  and 
the  effective  horsepower  available,  all  based  on  velocity 
of  advance  in  miles  JMT  hour;  also  a  curve  for  the  engine 
employed,  showing  brake  horsepower  plotted  against  rev- 
olutions per  minute; 

A  statement  of  the  type  and  principal  characteristics 
of  the  engine  proposed,  together  with  oil  and  fuel  eon- 
sumption  per  brake  horsepower  hour; 


264  TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


A  statement  of  the  performance  with  full  load  at  sea 
level  including:  Weight,  full  load;  useful  load;  maximum 
speed ;  load  in  pounds  per  square  foot  of  plane  area,  in- 
cluding ailerons;  load  in  pounds  per  horsepower;  climb 
in  10  minutes;  tank  capacities  for  fuel  and  oil;  endur- 
ance at  full  power  at  sea  level. 

The  aeroplane  must  have  construction  permitting  fa- 
cility of  observation,  inherent  stability,  ease  of  control 
and  comfortable  installation  for  the  crew. 

The  general  specifications  are  to  be  construed  to  include 
Bureau  of  Construction  and  Repair  and  Bureau  of  Steam 
Engineering  detail  specifications  in  effect  at  the  respective 
date.  All  materials  and  processes  are  to  be  in  accordance 
with  any  such  detail  specifications;  otherwise,  in  accord- 
ance with  trade  custom  as  approved  by  the  inspector. 

It  is  stipulated  the  contractor  shall  provide  all  material, 
parts,  articles,  facilities,  plans  and  data  to  conduct  all 
trials.  Non-metallic  materials,  such  as  dope,  glue,  var- 
nish and  ply-wood,  are  supplied  by  firms  on  the  approved 
list  of  the  Bureau  of  Construction  and  Repair. 

Inspectors  may  reject  peremptorily  any  inferior  work- 
manship or  material.  The  contractor  has  the  right  of 
appeal  to  the  Department,  whose  decision  is  final. 

The  contractor  is  obligated  to  furnish  under  the  con- 
tract, without  additional  cost,  such  samples  of  material 
and  information  as  to  the  quality  thereof  and  manner  of 
using  same  as  may  be  required,  together  with  any  assist- 
ance necessary  in  testing  or  handling  materials  for  the 
purpose  of  inspection  or  test.  The  passing  as  satisfactory 
of  any  particular  part  or  piece  of  material  by  the  inspector 
will  not  be  held  to  relieve  the  contractor  from  any  respon- 
sibility regarding  faulty  workmanship  or  material  which 
may  be  subsequently  discovered. 

As  soon  as  work  on  the  contract  is  started  the  contrac- 
tor is  on  request  to  prepare  for  approval  a  full-size  model 
of  the  cockpits,  showing  the  general  arrangement  and 
disposition  of  seats,  safety  belts,  controls,  instruments 
and  accessories  located  therein.  The  object  of  this  is  to 
test  the  feel  of  the  cockpit  for  roominess,  convenience  of 
control,  suitability  of  location  of  -all  parts  and  amount 
of  view  afforded. 

Engines,  armament,  instruments  and  accessories  will  be 
supplied  by  the  contractor  or  by  the  Department,  and  be 
installed  by  the  contractor  in  an  approved  manner  and 
location. 

The  engines,  armament,  instruments  or  other  fittings,  to 
be  supplied  to  the  contractor  by  the  Department  will  be 
free  of  cost,  but  the  contractor  will  be  required  to  fit  them 
in  the  machines  at  his  own  risk  and  expense,  and  be  solely 
responsible  for  carrying  out  successfully  the  requirements 
of  the  specification. 

Alterations  and  substitutions  will  be  permitted  only 
upon  the  approval  of  the  inspector  in  charge  but  wher- 
ever such  alterations  may  affect  the  contract  plans  and 
specifications,  the  aerodynamic  qualities,  structural  integ- 
rity, or  military  characteristics,  such  approval  must  be 
obtained  from  the  Department  through  the  inspector  in 
charge. 

All  changes  approved  by  the  bureaus  or  requested  by 
them  will  in  general  be  of  two  classes:  First,  those  of 
immediate  military  importance  or  necessary  for  safety, 
which  will  be  incorporated  in  all  units  at  once,  and  new 


parts  shipped  after  units  already  delivered,  so  that  the 
stations  may  incorporate  the  changes;  and,  second, 
changes  which  are  desirable  but  not  so  urgent  as  to  war- 
rant interference  with  production. 

In  case  of  the  first  three  machines  of  a  new  type,  all 
material  of  every  description  placed  on  or  attached  to  the 
aeroplane  is  to  be  weighed,  together  witli  all  material  of 
every  description  which,  after  being  weighed  and  placed 
on  or  attached  to  the  aeroplane,  is  removed ;  and  such 
weight  and  description  of  the  part  weighed  in  all  cases 
reported  to  the  inspector. 

Where  material  is  assembled  before  being  weighed,  the 
center  of  gravity  of  such  assembly  is  to  be  ascertained. 
The  center  of  gravity  of  each  part  or  group  of  parts  en- 
tering into  or  attached  to  the  aeroplane  must  be  reported 
in  relation  to  the  front  edge  of  the  lower  plane  with  pro- 
peller axis  horizontal. 

Parts  which  are  partially  or  completely  assembled  be- 
fore installation  are  photographed  and  prints  supplied. 
In  addition,  photographs  of  the  complete  assembly  are 
to  be  submitted,  giving  the  maximum  amount  of  detail 
in  not  less  than  four  positions. 

PLANS  AND  DATA 

One  set  of  general  arrangement  plans  shall  accompany 
each  aeroplane  for  use  in  erection,  together  with  a  set  of 
instructions  for  erection;  also  construction  specifications 
of  the  aeroplane;  specifications  and  statement  of  sources 
of  supply  of  all  wood,  veneers,  metals,  forgings,  stamp- 
ings, wire,  cable,  glue,  fabric,  dope,  paint,  varnish,  tub- 
ing, pulleys,  tanks,  etc. ;  description  of  practice  followed 
in  seasoning  wood  and  heat-treating  metal,  finishing  fabric. 
securing  fabric,  making  wire  and  cable  terminals,  rust- 
proofing  of  steel  parts,  waterproofing  of  wood  parts :  and 
statement  of  the  parts  that  have  been  brazed,  welded  or 
soldered. 

Landing  Gear 

The  landing  gear  must  be  of  an  approved  design  and 
construction.  Location  of  the  wheels  shall  be  such  as  to 
prevent  any  undue  "  spinning  "  when  landing  down  wind 
under  conditions  specified.  Particular  attention  will  be 
given  to  simplicity  of  design,  reduction  of  head  resistance, 
and  the  least  weight  consistent  with  the  service  intended. 

Staunchness  of  construction  is  required  while  disposing 
material  to  greatest  advantage,  transmitting  loads  by 
suitable  fittings  and  fastenings  into  the  principal  members 
and  through  them  to  the  structure  as  a  whole,  in  order  to 
obtain  strength  without  excessive  weight.  If  at  the  same 
time  resilience  can  be  obtained  it  will  be  an  advantage. 
and  shock  absorbers  may  be  employed  if  their  introduc- 
tion involves  improvement  in  performance.  Streamline 
form  is  desirable  but  must  not  be  permitted  to  affect  sea- 
worthiness. 

Water-tight  subdivision  is  required  as  well  as  suitable 
access  and  drainage  for  each  compartment.  Hulls  hav- 
ing double  bottoms  to  the  step,  are  to  have  suitable  drain- 
ing arrangements  incorporated  in  this  false  work.  Drain- 
plugs  and  handhole  plates  are  required  on  tail  and  wing-tip 
floats  as  well  as  on  main  floats.  Flying  boat  hulls  are. 
provided  with  a  hand  bilge-pump  and  means  for  pumping 
out  any  compartment  when  the  craft  is  adrift  at  sea. 
Double  skin  boats  shall  have  cotton  sheeting  and  marine 


NAVY    DKI'AHTMKXT   AKKOIM.AN  K  SI'K(  1 1  1C  A  1  K  >N  s 


glue  U-tween  tin-  plvs.  Hulkhcads  should  In-  utilized  AS 
.strength  incinlirrs  :uul  he  reason. ihlv  w  all  r  tight  for  at 
least  twelve  hours. 

'I'lir  form  "I  tin  liiittnin  should  be  such  as  ID  permit 
casv  planini:  Hilli  longitudinal  control.  Tin  Inrui  slionlil 
:I|MI  !»•  such  is  In  rrilurr  tlir  shock  of  landing  or  of  run 
ning  .it  high  speed  on  lough  water.  Tin  stahilitv  when 
afloat  ill  .-i  nnuli  r  id  M -a  with  alii  our  compartment  of  nilV 
omplclcly  or  partially  Hooded,  slinnlij  In-  such  that 
tin-  seaplane  will  not  roll  or  tip  ti\rr.  1'rovision  is  re 
(|iiirrd  against  bursting  dm-  to  tin-  change  in  pressure 
involved  in  ascending  to  tin-  maximum  altitude  contem- 
plated in  tin-  ili  si^n.  anil  tin  lirst  lloat  of  a  new  type  may 
iectcd  to  in  internal  pressure  corrcspondiii'.;  to  this 
altitude.  Suitable  skills,  kn-N,  edge  strips,  footliolils. 
walking  sirips,  etc..  an-  required  to  prr\cnt  undue  chafe 
ami  we.-ir  in  service.  Towiny  cleats  .mil  nose  rings  shall 
In  "I  :ipprii\cil  design  ami  location. 

All    internal   nirtal    lillin^s   ami   all    fastenings   shall   lie 
copper  or  brass,  ami  all  •  \ti  rnal  metal  |iarts  shall  1'e  ade 
quatclv    proteelnl    against    the   action   of   salt    water. 

llolis  lor  fastenings  are  to  he  carefully  bored  and  care 
(akin  I"  avoid  splitting  the  wood.  Units  and  clinched 
lioal  nails  are  to  I  r  used  in  preference  to  screws  wher.  \er 
possilile.  1  )i  id  nails  are  not  to  he  used.  dim-  should 
not  he  n  lied  upon  as  a  jointing  material  in  any  lioat  or 
float  work.  Anv  splice,  in  strength  nu  inU-rs  must  IM- 
.secured  hy  copper  rivets  and  if  possible  In  whipping  ill 
addition.  The  type  of  splice  shall  in  any  case  he  sub- 
mitted  for  approval.  Any  propeller  which  has  not  a  float 
directly  heneath  it  is  to  he  so  situated  that  clearance  IM-- 
the  propeller  tips  and  the  water  is  not  less  than 
two  ft.  when  the  seaplane  is  afloat  at  rest,  or  is  afloat 
1  with  the  tail  lifted  to  the  Hying  attitude  Pro- 
peller clearance  immediately  over  floats  should  be  at  least 
two  in. 

Body 

The  form  and  disposition  of  body  members  and  fittings 
are  such  as  to  provide  positive  alignment  and  minimum 
distortion  under  the  loads  to  IM-  met  in  service.  For  sea- 
plain  s.  the  crew  must  IK-  able  to  get  out  quickly  in  cas, 
idcnt.  Suitable  footholds  are  to  be  provided  to 
enable  (lie  crew  to  pass  to  the  main  floats  and  to  the 
engines  to  make  minor  adjustments  while  the  machine  is 
afloat. 

Longitudinals  may  In-  spliced  only  in  approved  manner. 
Longitudinal  fittings  shall  IM-  properly  anchored  to  take 
shear,  but  through-bolts  should  be  used  with  caution.  All 
wins  used  for  trussing  arc  to  IM-  solid  except  where  read- 
ily acctssiblc.  or  where  the  use  of  other  types  is  ap 
i.  A  suitable  windshield  is  to  In-  fitted  to  each 
cockpit.  For  each  seat  an  apprised  safety  !M-||  will  be 
supplied.  Kcmoxahlc  seat  cushions  are  to  IK-  so  attached 
that  they  cannot  shift  when  in  flight. 

Engine  Installation 

1'or   seaplanes    the    engines    shall    be   capable    of   being 
•  1  by   the  crew   when  the  machine  is  afloat   in  a  sea- 
way.     The  engines  shall   lx-  accessible  and  easily   removed 
and   replaced   as   a   unit    with   a   minimum  disturbance  of 
fittings. 

Kngincs  arc  to  be  effectively  cowled  with  sheet  metal, 


with  parts  easdx  remo\able  for  access  (  owls  for  rotary 
engines  shall  protect  crew,  planes  mil  Uxly  from  oil  and 
smoke  Tin  exhaust  is  not  to  interfere  with  tin  crew,  nor 
is  (here  to  lie  any  1 1. -1111:1  r  of  fire  due  to  it. 
mufflers  are  to  be  provided  unless  s|M-cfically  <  xei -pled. 
Approved  provision  is  to  I.,  in  idi  tor  the  .nlrin. 
exit  of  air  for  the  purpose  of  cooling  |h,  ,  ML:mc  base 
and  cylinder  heads.  In  tractor  aeroplanes  a  flame  tight 
metal  bulkhead  immediately  hi  Inn. I  the  engine  is  provided. 
Means  are  installed  in  the  pilot's  cockpit  for  extinguish- 
ing lire  forward  of  tile  fire  bulkhead.  The  body  beneath 
•lyine  has  a  imial  cover  sloping  In  the  rear  with  an 
opening  at  the  r.  .r  .  il^.  extending  the  entire  width.  The 
Ivottom  of  the  body  hi  hind  this  point  is  to  be  ..,\,  red  »ith 
metal  for  at  least  three  feet.  Suitable  drip-pans  and 
drainpipes  leading  clear  of  the  body  are  to  lie  provided  to 
get  rid  of  gasoline  overflowing  from  the  carbureters  or 
elsewhere.  Carl  ureter-float  covers  shall  be  so  si  cured  as 
to  prevcir  ,.l  ^'isoline.  Careful  consideration 

should  he  given  to  conditions  surrounding  air  supply  to 
the  earbureti  r  In  insure  that  spray  and  rain  are  not  drawn 
in  anil  that  freezing  dix-s  not  o.-ciir  in  the  carbureter  or 
induction  pipes  at  high  altitudes. 

A  head  of  at  least  .'.  in.  shall  remain  above  the  outlet 
li  cylinder  when  the  reserve  water  allowed  has  been 
boiled  away  or  otherwise  lost,  and  with  the  machine  in- 
clined upward  -' '•  (leg.  to  horizontal,  or  K)  deg.  list  to 
either  side.  Radiators  shall  be  tested  filled  with  air  at 
S  Ihs.  per  sij  in.  pressure  when  totally  immersed  in  water. 

Foundations 

All  foundations  for  engines,  radiators,  seats,  control 
gear,  guns.  I., .nil.  storage,  releasing  gear.  etc..  are  to  IM- 
thoroughly  supported  from  panel  points. 

Fuel  Tanks,  Piping,  Etc. 

Fuel  tank  location  is  nearly  central.  Gravity  feed  to 
irburetor.  under  normal  conditions  of  flight,  or  a 
service  tank  having  at  least  a  half-hour  capacity,  is  pro- 
vided. I  .11  h  tank  has  independent  leads  either  to  the 
service  tank  or  carbureter.  If  gravity  feed  cannot  IM-  ob- 
tained, proper  and  approved  means  in  addition  to  a  hand- 
pump,  are  provided  for  supplying  the  service  tank.  F.rfi- 
cicnt  strainers  arc  required  in  each  fuel-tank  lead.  All 
solid  piping  shall  IM-  annealed  after  bending.  All  joints 
shall  IM-  brazed. 

Fuel  tanks  shall  be  tested  with  an  air  pressure  to  give 
three  pounds  per  square  inch  at  the  carbureter  without 
showing  leaks  or  unreasonable  deformation.  Swash-plate 
bulkheads  should  IM-  tilted  and  the  heads  so  formed  n»  to 
prevent  vibration.  If  gravity  feed  is  used,  the  tank  shall 
IM-  fitted  with  a  suitable  vent,  which  will  close  mil  pre- 
vent leakage  of  gasoline  through  the  vent  in  case  the  air- 
plane turns  upside  down.  Tanks  shall  IM-  non  corrosive 
and  made  of  annealed  material  where  possible.  Filling 
caps  are  to  IM-  secured  with  chain  lanyards. 

All  gasoline,  oil  and  air-pi|M-  joints  are  to  IM-  electro- 
conductive,  .-md  where  the  joint  has  to  lie  made  with  an 
insulator,  such  as  rubber  tubing,  it  must  IM-  short  circuited 
by  an  approved  method.  The  gasoline  and  oil  supply  are 
to  be  so  arranged  that  the  delivery  of  gasoline  and  oil  will 
continue  under  the  normal  air  pressure  (if  no  fitted)  until 


266 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


the  tanks  are  empty,  in  any  reasonable  position  of  the 
machine.  The  ignition  and  auxiliary  circuits  must  be 
thoroughly  protected  from  short-circuits  by  spray.  A 
positive  means  of  quickly  cutting  off  the  gas  at  the  serv- 
ice tank  shall  be  readily  accessible  from  either  seat.  The 
fuel  leads,  the  control  leads,  and  the  carbureter  adjusting- 
rod  shall  be  provided  with  suitable,  safe  and  ready  coup- 
lings where  those  connections  have  to  be  frequently  broken. 
The  oil  thermometer  bulb  shall  be  installed  in  the  oil- 
sump  or  other  approved  location  where  it  shall  be  covered 
with  oil  at  all  times.  The  circulating-water  thermometer 
bulb  shall  be  installed  in  the  outlet  pipe  of  the  engine 
near  the  radiator,  or  in  other  approved  location. 


Controls 

Plans  showing  the  general  control  system  shall  be  ap- 
proved before  installation.  All  control  gear  and  control 
cable  shall  be  readily  accessible  for  inspection  and  lubri- 
cation. The  control  surfaces  and  actuating  mechanism 
shall  be  so  arranged  that  under  no  circumstances  shall 
they  jam  or  foul,  and  the  whole  system  shall  have  an 
approved  margin  of  strength  and  rigidity. 

All  control  gear  shall  be  so  placed  that  it  will  be  pro- 
tected from  sand  and  dirt.  Control  wire  shall  be  kept 
away  from  floors. 

All  control  operating  horns  shall  be  relieved  of  bending 
stress  by  at  least  one  wire  unless  otherwise  approved, 
and  control  columns,  posts,  bars  and  pedals  shall  be  pro- 
portioned to  prevent  bending  in  service. 

Welding  of  control  horns  is  prohibited  except  for  longi- 
tudinal seams. 

All  control  leads  shall  be  of  stranded  cable  of  an  ap- 
proved flexible  type  and  make,  and  shall  be  thoroughly 
stretched  before  fitting.  Where  the  control  lead  passes 
around  a  pulley  or  drum,  the  wire  shall  be  guarded  against 
coming  off.  Such  guard  will  not  be  approved  if  the  cable 
can  be  forced  off  its  pulley  or  drum  when  quite  slack,  by 
pushing  the  two  ends  of  the  cable  inwards  with  the  hands. 
All  control  pulleys  shall  have  ball  bearings.  The  radius 
of  curvature  of  pulleys  or  fair  leads  for  control  wires 
shall  be  not  less  than  fifteen  diameters  of  the  wire  for  a 
90  deg.  bend.  The  turnbuckles  in  control  wires  shall  be 
in  approved  positions  as  far  as  possible  from  the  compass, 
and  accessible  for  adjustment. 

The  handwheel,  if  employed,  shall  be  made  exclusively 
of  non-magnetic  material  with  the  inner  edge  of  the  rim 
corrugated.  The  rim  shall  be  fastened  in  a  secure  man- 
ner and  the  use  of  wood  screws  for  this  purpose  will  not 
be  allowed. 

Each  elevator  half  is  to  be  provided  with  one  pair  of 
operating  horns  (or  their  equivalent),  each  with  independ- 
ent leads. 

The  steering  is  to  be  by  means  of  foot  bar  or  pedals, 
adjustable  fore  and  aft  for  at  least  six  inches.  Arrange- 
ments are  to  be  made  to  prevent  the  pilot's  foot  slipping 
off  the  foot  bar  or  pedal.  If  a  foot  bar  is  used,  guides 
are  to  be  fitted  to  prevent  vertical  play;  also  stops  suffi- 
ciently high  and  strong  to  prevent  the  bar  bending  or 
overriding  them. 

The  controls  need  not  be  non-magnetic  for  the  trials, 
but  if  the  compass  is  affected,  replacement  with  non-mag- 
netic gear  is  to  be  made.  The  fixed  control  fittings  should 


preferably  be  non-magnetic,  but  permission  may  be  given 
to  use  magnetic  fittings  if  it  is  considered  that  there  will 
be   an   advantage   in   weight,   strength   or    convenience 
manufacture. 

If,  on  the  engines  employed,  the  throttle  and  magr 
advance  levers  are  interconnected  and  brought  to  a  single 
lever,   this   lever   shall   be   operated   by   a   separate   hand- 
lever   for  each   engine.     When   the  throttle   and   magneto 
are    not   interconnected,    a    separate    hand-lever    shall    be 
provided  for  each  engine,  these  systems  being  so  arranged 
that  the  pilot  can  control  with  one  hand  the  engines  in- 
dividually or  together.     The  hand-levers  to  the  throttle 
and  ignition  and  to  the  engine   switches,  in  case  of  ma- 
chines carrying  two  or  more  pilots,  shall  be  arranged  by 
duplication  and  interconnection  of  levers,   so   that   either 
pilot  can  operate  them  when  in  flight.      The  forward  posi- 
tion is  to  be  the  position  for  full  power.     Each  throttl 
or  magneto  advance  lever  is  to  be  fitted  with  an  approved 
system  of  positive  location.     A  spring,  capable  of  open- 
ing the  throttle  in  the  event  of  the  control  gear  breaking, 
is   to  be   fitted  at  the  engine  end   of  the   throttle-control 
system.     The  engine  switches  are  to  be  of  an  approved 
type  and  so  placed  for  each  engine  that  all  can  be  moved 
simultaneously   with   one   hand,   the   direction   of   motion 
for  shorting  to  be  approved.     Ground  wires  for  switches 
are  to  be  led  direct  to  the  engine  and  not  to  the  engine 
mounting. 

Wings 

Spruce  or  Port  Orford  cedar  for  wing  spars  shall  be 
selected  from  the  clearest,  finest  stock  available,  shall 
have  a  density  in  excess  of  0.36  and  0.42,  respectively, 
based  on  oven-dry  weight  and  volume,  and,  if  possible, 
more  than  eight  rings  per  inch. 

The  spar  shall  be  suitably  increased  in  dimensions  where 
it  is  pierced  by  bolts.  Particular  attention  is  to  be  given 
to  this  point  when  the  spar  is  pierced  by  bolts  not  approx- 
imately on  the  neutral  axis.  The  fitting  and  its  method 
of  attachment  to  the  spar  shall  be  so  designed  that  the 
failure  of  any  part  of  it  shall  not  cause  the  struts  to  be 
displaced  or  both  the  flying  and  stagger  wires  to  be  re- 
leased. 

Either  brass  or  galvanized-iron  brads  shall  be  used  '• 
fasten  cap  strips  to  ribs;  but  brass  screls  shall  be  used 
to  fasten  cap  strips  to  spars. 

In  order  to  prevent  relatively  weak  portions  of  the 
machine  from  damage  in  handling,  hand-grips  shall  be 
fitted  in  suitable  positions  near  the  extremities  of  the 
lower  planes. 

Control  Surfaces 

All  ailerons  shall  be  double-acting.  For  large  machines 
in  which  control  by  means  of  unbalanced  surfaces  will  be 
obtained  with  difficulty,  balanced  surfaces  of  approved 
form  shall  be  provided. 

The  horizontal  fixed  tail  surface  shall  be  so  designed  as 
to  permit  of  adjustment  in  angle.  Arrangements  may  in 
some  cases  be  made  for  this  adjustment  while  in  flight. 

Elevators  shall  be  on  same  axis  tube  or  locked  together 
in  such  a  manner  that  the  control  is  not  rendered  useless  if 
one  set  of  control  wires  breaks. 


Wing  Struts 
Wooden  wing  struts,  if  hollow,  shall  be  taped,  dopec 


NAVY   DKl'AirrMKNT  A  Kl«  >1M..\  \  I     SPE4  II  li    \l|«,\s 

and   xarmshed.      Any    •**«*«  subtly    warped   will   be      operated   bx    -,„„, „„-    ,,,,mrtlMcnt  mnv 

rejected.      \    ooden   ,,ru,   shall     ,d,    .,  .„,„,„        ,,„,.,,,   „,  „,  £J 

spruce.    I'ort    Ortord   cedar  or   white   ,,„„-   of   finest   grade.        .ilenm  load*. 


close  grained    ind  Hell  -eason,  ,i.       I  or  struts  the  inspector 
will  select  -prucc  or  white  |>itic  ha\ing  :i  <j<  n-jt\   in 
of  (>.. 'Hi  or  I'ort  Orford  c,  dar  li:i\iu^  a  dcn-itv  in  excess  of 
and.  if  possible,  more  than  eight   rinijs  per  inch. 

Propellers 

Tli.    propeller   hub   fncepl.it,-,   shall   be   intcrconn 
imlcpi  -ndent.y  of  tin-  propeller  bolts,  so  that  each  plate  is 
used    to    drix,     the    propeller.      Wood    propellers    shall    be 
fitted  with   sheathing  wlii<-h   sh.-ill  extend  a  distance   from 


The  total  lift  load  ..n  each  wing  in  ih.    product  of  thr 
•f  that  wing  by   it,  i,.,,t   load    ,n,l   „   a ,-„„,.  d   to  U- 
applied  uiiifonnly  .ilonK  the  -pars  .-,,l(|  di-trihulcd  b. 
them   ,„   imrr-c  pro|M.rlion  to  their  chord  di-lancc,   from 

•'MM.  ,1  center  of  pressure.      At   high   -p,,-,|   i|,, 
t.  r  of   pressure   -lull   IH-  assumed  at  (»..'.   of   the  chord   di, 
In...     from    the    leading  ,  ,,t    when    r,.|,  ,|,|(.    „„„, 

tunnel  data  on  the  center  of  pressure  trax.l  and  „„„„, 
plane  life  .-..crticicnts  for  the  aerofoil  employed  are  axail 
able,  in  which  ease  the  center  of  pressure  for  high 


Non-corrosive 


the  tip  of  the  1.1.1,1,    toward  the  center  approximately   on,          mix    l«-   calculated    from   the   wing   loading    it    high 

rth  the  diameter  on  the  leading  edge  .md  ,-ight  inehes  by  obtaining  the  riving  angle  from  the  monoplane  lift 
on  the  trailing  edi;.,  is  a  iiiininiuiii ;  detailed  requirement-  characteristic.  At  low  -|H-ed  the  center  of  pressure  shall 
may  be  found  in  Bureau  of  Steam  l-'nginci-ring.  Instriic-  be  taken  at  (l.-.'H  of  the  chord  distance  from  the  I. 

edge,   mil,  ss   an   unusual    aerofoil    i-   employed,    in    which 
•he  center  of  pressure  travel  may  be  modified  if  data 
from  wind  tunnel  tests  are  available. 

I!. -ides  the  lift  load  defined  alx.xe.  the  wings  carry  a 
drift  load  which  may  U-  assumed  equal  to  one-quarter  the 
lift  load  and  applied  at  the  center  of  pressure.  Tin-  drift 
is  assumed  to  include  the  drift  of  wings,  struts,  wir- 
ap|H-ndages.  \Vherc  data  from  wind  tunnel  test*  arc 
quoted,  the  fraetion  of  lift  applied  horizontally  as  drift 
may  be  altered.  Thi.s  drift  load  may  then  IN  dni.l.d 
Let  ween  the  spars  and  distributed  uniformly  along  them. 
Kesolve  the  running  lift  and  drift  loads  for  each  spar 
into  a  single  running  load  in  the  plane  of  the  principal 
axis  of  the  spar  and.  making  use  of  the  Theorem  of  Three 
Moments,  compute  the  bending  moments  in  the  spar  and 
the  reactions  at  the  joints  or  points  of  support 

Assume,  as  a  first  approximation,  pin  joints  with  all 
loads  concentrated  on  joints  and  compute  direct  sir. 
each  member  after  having  nsoUed  (he  loads  into  the 
planes  of  each  group  of  member-  i.  c..  plane  of  front 
struts,  plane  of  chord  of  top  wing,  ete.  For  apart,  com- 
bine the  direct  -tresses  due  to  lift  and  to  drift  with  the 
stress  due  to  bending. 

The  horizontal  ihrar  in  the  wing  spar-  -hould  br  com- 
puted for  section-  near  the  strut  ends  where  the  »par  h*« 
its  usual  section. 

Directly  over  the  strut-  the  wing  spars  shall  not  he 
hollowed  out.  and  if  pierced  by  holt  holes  allowance  -hall 
be  made  in  all  computations  for  the  sectional  area  of  the 
holes.  Wood  spars  of  I -section  shall  have  the  web  at 
least  equal  in  thickness  to  the  flanges  and  eut  with  gener- 
ous fillets. 

All  splices  iii  solid  wing  spars  shall  be  loeated  at  (mints 
of  eontratlexiire  or  minimum  bending  moment.  When  the 
exaet  location  of  these  points  is  not  known,  they  may  be 
assumed  to  oeeur  at  from  one-fourth  to  one-third  the  dis- 
tance between  consccutixe  interplane  struts 

Splicing  of  iml.iiiun.it,  d  spars  or  of  lamination*  of  lam- 
inated spars  will  be  permit  ted  provided  the  type  of  spin, 
is  appro* cd  by  the  Department. 

In  splicing  solid  wood  spars  of  I-section  the  spliced  fee- 
lion  shall  not  le  routed  out. 

Fittings  for  pin-joints  at  butts  of  wing  spars  are  to  be 
designed  so  that  securing  bolts  cannot  crush  or  shear 
through  wood  under  loads  specified  below. 


tion-     for    Tipping    Seaplane     Propellers. 
riiet-  or  screws  shall  IK-  used. 

FACTORS  OF  SAFETY 

factors  of  safety  specified  apply  in  general  to  all 
aeroplanes.  In  all  case-  the  burden  of  proof  rests  upon 
th,  contractor  to  demonstrate  by  submission  of  his  calcu- 
lations in  detail  that  the  aeroplane  is  structurally  safe. 
Any  part  or  parts  whose  strength  is  in  doubt  shall  be 
tested  by  sand  loading  or  other  approved  method.  Thi.s 
specification  refer-  in  particular  only  to  the  most  impor- 
tant structural  members.  I'or  foundations,  terminals,  tit- 
ting-,  bra,-,-  and  minor  structural  parts,  for  which  calcu- 
lation- an  indeterminate  01  loading  unknown,  good  en- 
gine, ring  practice  shall  be  followed. 

Th,   wing  truss  con-i-t-  of  the  wing  spars,  interior  brae- 
rut-  and  exterior  bracing  together  with  all  wire  or 
cable  anchorage-,  but  does  not  include  non-strength  parts. 
such     is    leading  and   trailing  edge   strips,   ordinary    ribs, 
tap,,  doth,  battens,  corner  blocks  and  fairing  pieces.      It 
nned    that    the    wing   truss   carries    in   normal   flight 
the  full  weight  of  the  aeroplane  and,  in  addition,  the  drift 
of  the  wings,  struts,  external  wires  and  any  appendages, 
such  as  skid  fins,  wing  floats,  etc. 

In   biplanes   the  distribution   of  loading  on   the   wings 
shall  Ix-  computed  by  the  formula: 

11 

-  +  AX,  (i) 

9 

in  which  W  =  total  lift  load,  A*  =  area  of  upper  wing, 
=  area  of  lower  wing,  and  x  =  unit  load  on  the  lower 

which  is  obtained  by  solving  the  above  equation. 
In   triplanes   the  distribution  of  loading  shall  be  com- 
puted by  the  formula: 

5  3 

W  =  A-x—  -f  A-x—  +  Ax,  ( 2 ) 

*  4 

in  which  A"  =  area  of  middle  wing,  and  other  notation  is 
••  me  as  in  ( I ) . 

-tresses  imposed  in  the  wing  truss  are  figured  from 
•   lift  which  equals  the  total  lift  less  the  weight  of 

md  the  interplane  bracing. 

Aileron-   are  considered   as   wing  area,   but  in   special 
when   ailerons   are   of   unusual   design   or   si*e.   or 


268 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Struts  shall  be  computed  as  if  made  with  pinned  ends 
whether  or  not  the  ends  are  actually  pinned. 

For  it-ires  and  cables  allowance  should  be  made  for  the 
efficiency  of  the  terminal.  Similarly,  the  strength  of  the 
fitting  to  which  the  wire  or  cable  terminal  is  secured  must 
be  considered  in  the  wing  truss  design.  Wires  and  cables 
should  be  so  led  as  to  introduce  no  eccentric  loading  on 
structural  members  and  anchored  in  fittings  designed  to 
develop  their  full  strength. 

The  stagger  wires  are  to  be  assumed  to  carry  the  drift 
of  the  top  plane.  Where  the  top  plane  passes  over  the 
body,  the  entire  drift  of  the  top  plane  is  assumed  to  be 
carried  into  the  body  by  the  stagger  wires  and  struts  at 
that  place  as  if  acting  alone. 

Cross  transverse  diagonal  wires  over  the  body  holding 
the  top  plane  from  racking  as  the  aeroplane  rolls  should 
be  computed  to  hold  the  rolling  movement  obtained  by  as- 
suming an  up  load  of  20  Ibs.  per  sq.  ft.  on  one  set  of 
ailerons  and  an  equal  down  load  on  the  opposite  set. 

Wood 

Air  seasoning  is  preferred,  but  forced  drying  will  be 
permitted  if  approved  methods  are  used.  Laminated  wood 
shall  not  be  used  unless  approved  by  the  Department. 
Spiral  grain  will  be  allowed  only  as  permitted  in  specifi- 
cations issued  by  the  Department  for  each  type  of  ma- 
chine in  production,  and  in  case  of  doubt  test  sticks  shall 
be  split.  No  spruce  or  white  pine  below  0.36  density, 
Port  Orford  cedar  below  0.42  density,  or  ash  below  0.56 
density  in  oven-dry  condition  shall  be  used  in  important 
strength  members.  Wood  splicing  shall  be  only  as  ap- 
proved. The  splices  shall  be  of  efficient  form  and  the 
grain  shall  not  be  turned.  Bolts  or  rivets  shall  be  used 
if  required,  and  the  joints  shall  be  finally  taped  or  served 
and  glued  as  prescribed. 

All  dope,  enamel,  paint,  varnish,  shellac,  waterproof, 
hide  or  marine  glue  shall  conform  to  Department  specifi- 
cations. 

Metals 

Where  the  material  is  of  a  class  susceptible  of  improve- 
ment in  quality  by  heat  treatment,  such  treatment  shall  be 
given  as  a  final  step  in  manufacture,  except  in  the  case  of 
small  parts.  In  the  latter  case  the  heat  treatment  shall,  if 
practicable,  be  given  before  fabrication  or  else  the  parts 
shall  be  made  from  heat-treated  stock. 

Steel  shall  not  be  left  in  finished  parts  in  a  hot-rolled, 
hot-forged,  or  cold-forged  condition.  Normalized  steel 
must  be  renormalized  after  forging  (hot  or  cold),  welding, 
or  otherwise  heating. 

Hard-drawn  steel  must  not  be  heated. 

Laminated  fittings  of  metal  which  are  brazed  or  welded 
shall,  in  addition,  be  thoroughly  riveted.  Welding  and 
brazing  shall  be  restricted  to  parts  not  otherwise  possible 
of  fabrication,  and  only  in  approved  locations. 

Acids  will  be  used  in  soldering  only  where  expressly 
permitted.  If  used,  after  soldering,  all  acid  shall  be  neu- 
tralized and  washed  out  in  an  approved  manner. 

Wire 

Solid  wire  shall  be  carefully  formed  to  perfect  eyes 
without  any  rebending,  and  the  eyes  shall  be  properly 
formed  to  prevent  crawling.  Eyes  should  be  examined 


for    signs    of   lamination    and    cleavage.      Cable    shall    be 
tacked  with  solder  before   cutting  or  cut  with   acetylene  , 
flame  to  prevent  uneven  stress  due  to  unlaying.     At  the 
time  of  tacking  the  wire  shall  lead  straight. 

Wire  with  hemp  centers  shall  have  the  center  locally] 
removed  before  making  up  the  terminals  so  that  the  cen-l 
ter  strand  will  carry  no  load.  The  ends  of  all  cables, 
whether  flexible  or  otherwise,  shall  be  fitted  with  thimbles 
or  other  approved  device  to  minimize  slackening  in  serv- 
ice. Where  cone  cups  are  used  for  terminals  the  double  i 
mushroom  may  be  required  unless  the  workmanship  is 
such  as  to  show  by  test  perfect  terminals  in  every  case. 
Taper  plugs  shall  not  be  used.  All  wire  terminals  except 
those  of  the  cone-cup  type  shall  be  soldered.  Cone  cups 
will  be  puddled  with  zinc  and  care  taken  to  prevent  draw- 
ing the  temper  of  the  wire. 

Wherever  wires  are  inaccessible  for  adjustment,  as  is! 
the  case  inside  the  wings  and  auxiliary  surfaces  or  in 
parts  of  the  body  or  floats,  solid  wire  shall  be  used  un- 
less otherwise  approved. 

Cable  stays  shall  be  made  up  complete  witli  terminals 
and  proof  stretched  before  installation  with  a  load  equal 
to  one-quarter  of  the  ultimate  tensile  stress. 

Fabric 

Wing,  body  and  auxiliary  surfaces  shall  be  covered  with- 
linen  or  cotton  conforming  to  Aeronautical  Specifications, 
C  &  R  Nos.  12  and  13,  respectively.  On  the  wings,  the 
fabric  shall  be  applied  either  diagonally  or  with  stains 
running  normal  to  entering  edge.  On  the  wings,  the 
tape  and  lacing  method  shall  be  used,  with  loops  spaced 
not  more  than  four  inches  apart.  The  thread  shall  be 
knotted  at  each  loop  or  made  fast  with  a  double  half-hitch. 
and  then  cemented  with  dope.  The  tape  used  in  wing 
construction  shall  be  of  the  same  quality  of  fabric  as  used 
for  the  wings.  Tape  used  on  laminated  struts  or  built-up 
parts  shall  be  applied  with  glue  and  then  doped.  Thread 
used  for  stitching  seams  shall  be  of  an  approved  linen  or 
silk  and  shall  be  waxed. 

Pontoon  Fabrics 

In  built-up  laminated  floats,  bottom  planking  and  bulk- 
heads shall  include  cotton  sheeting  applied  with  an  ap- 
proved grade  of  marine  glue  between  laminations. 

Requirements  of  Finishing  Materials 
Acetate  and  nitrate  dopes  used  on  all  work  shall  be  ifl 
accordance  with  Aeronautical  Specifications,  C  &  I 
1    and    2,    respectively.     Spar    varnish    and    naval    gray 
enamel  used  on  all  work  shall  be  in  accordance  with  Aero- 
nautical Specifications,  C  &  R  Nos.  3  and  4A,  respectively. 

Doping 

The  doping  of  all  naval  planes,  with  the  exception  oj 
H-16  and  F-5,  shall  conform  to  the  Navy  Standard  Dop- 
ing System  A. 

Navy  Standard  Doping  System  A 

Wings,  control   surfaces   and   fuselage   fabric  —  On   all 
fabric    two    coats    of    cellulose    acetate    shall   be    applied 
This  treatment  shall  be  followed  by  the  application  of 
sufficient  number  of  coats  of  cellulose  nitrate  dope  —  no 


NAVY   DKl'AHTMKNT   AKKOI'I.ANK  SIM-.C  1 1  It  ATM  )\  > 


le-s  than  two  or  more  than  four  coats  —  to  obtain  satis 
factory  tautncss  and  tinisli.  After  the  last  coat  1ms  dried 
for  nut  less  than  twelve  hours.  na\:tl  gray  rnamel  .shall 
he  applied:  two  .-oat-  on  \crtical  surface,  two  coat-  ,IM  top 
sides,  and  on.-  coat  on  the  under  side  of  horizontal  sur- 
faces. 

()»  I'  l">  '"'I  I  •  planes,  acetate  dope  shall  conform  to 
Navy  Doping  System  B. 

Navy  Doping  System  B 

Wings,  control  surface-  and  fuselage  fabric  —  On  all 
fabric  the  successive  eoat>.  of  cellulose  acetate  dope  shall 
he  applied.  After  the  last  coat  has  been  dried  for  not 
less  than  twelve  hours,  naval  gray  enamel  -hall  lie  ap- 
plied; two  coats  on  vertical  surface,  two  coats  on  top 
.sides,  ami  one  coat  on  the  under  side  of  horizontal  sur- 
faces. 

Finish  for  Metal  Parts 

Plating  '/.'me  coating  is  preferred  and  should  be  used 
wherever  practicable.  When  galvanizing  is  employed,  the 
zinc  coating  should  conform  to  Aeronautical  Specification-. 
I  \  H  No.  ;;<>.  Special  alloys  and  heat-treated  steels  may 
l>e  affected  if  galvanized  by  the  hot-dip  or  other  proc- 
esses  employing  high  ti-mperatures  —  375  to  -150  deg.  C. 
On  such  parts,  as  well  as  on  accurately  dimensioned  small 
parts,  the  electro-galvanizing  process  (zinc  plating) 
should  In  given  preference. 

I  'leaning  —  Sand  blasting  is  preferred  for  cleaning 
metal  previous  to  plating.  Pickling  of  metal  surfaces  with 
acid  should  be  avoided  wherever  possible,  since  pickling 
increases  the  brittleness  of  metal  and  has  a  very  unfa- 
voral-le  effect  on  thin  stock.  Pickling  should  especially 
be  avoided  on  metals  that  may  IK-  subjected  to  continual 
vibration.  Wherever  pickling  is  used,  the  metal  should 
I"  thoroughly  cleaned  with  water  so  as  to  remove  the 
pickling  acid  previous  to  plating  or  finishing.  Threaded 
and  bra/ed  parts  are  often  cleaned  satisfactorily  in  tum- 
blini;  barrels  with  oil  and  emery. 

Painting  —  After  plating  or  coating  with  zinc,  copper 
or  nickel,  metal  fittings  .shall  IK-  finishcl  with  enamel. 
Specifications  ('  &  R  No.  lA  gray  or  No.  :>  black.  After 
assembly  all  metal  parts  that  show  bare  places  shall  be 
touched  up  with  enamel.  Interior  plated  or  zinc-covered 
fittings  such  as  tubes  or  aileron  horns  and  all  such  parts 
having  cavities  shall  lie  dipped  in  enamel  and  then  allowed 
to  drain  and  dry.  This  process  is  included  to  insure  in- 
terior protection  against  corrosion.  Steel  tubes  having 
sockets  or  caps  on  the  end  may  be  drilled  with  two  hoi 
Thinned  enamel  may  be  poured  in  one  hole  and  allowed 
to  drain.  After  enamel  is  dry  the  holes  should  In-  plugged. 

Wires  and  Cables 

All  fixed  external  wires  or  cables  shall  be  carefully 
cleaned  and  coated  with  spar  varnish  containing  5  per 

of  Chinese  blue. 

All  fixed  internal  hull  wires  or  cables  and  all  internal 
wing  wires  or  cables  shall  be  painted  with  naval  gray 
enamel. 

All  control  wires  or  cables  shall  be  heavily  coated  with 
an  approved  grease. 


RULES  GOVERNING  CONDUCT  OF  TRIALS 

I  1<H,,1        Comprises   the  aeroplane  complete   in  or 
•  ler  for  flight,  includim;  water  in  radiators,  water  and  oil 

tl"r" "t-rs.    tachometer,    dashboard    instruments,    stnrt- 

ers,   all   tanks   and   gages   and   armor,    but    without    those 
items  included   m       t  scful  load." 

{•'nil  load  —  Comprise..  ()„•  aeroplane  complete  us  speei 
fied  under  "  Light  load  "  and  in  addition  the  I  seful 
load." 

{'*rfnl  load  —  Comprises  fuel  and  oil.  crew,  armament, 
equipment  and  accessories  as  detailed  in  the  com, 

At  the  beginning  of  each  trial  of  any  performance,  the 
aeroplane  shall  be  brought  to  the  prescribed  "  I  nil  load  " 
condition. 

The    first    successful    trial    under    the    conditions    pr. 
scribed  shall  be  final,  and   no   further  attempts   shall    I . 
made. 

Throughout   the  trials  the   powerplant    (including   pro- 
peller)  and   the  aeroplane  shall   be  identical   in  even    r. 
spect  with  that  which  it  is  proposed  to  deliver  for  KH 

The  gasoline  used  shall  be  of  a  commercial  grade  read- 
ily procurable. 

Demonstration  trials  include  the  following,  in  which 
the  aeroplane  .shall  meet  the  |x-rformancc  requirements  of 
the  contract: 

(a)  High  speed,  (t)  Climbing,  (r)  Maneuvering  on 
the  surface  and  (d )  Maneuvering  in  the  air. 

Immediately  after  each  trial  an  inspection  of  the  aero- 
plane and  powerplant  shall  be  made  to  determine  that  all 
parts  arc  in  good  condition  and  functioning  proper! v. 

Not  more  than  four  official  attempts  will  be  allowed  in 
which  to  make  either  the  high  speed  or  climb  prescribed. 

The  manner  of  conducting  the  high  speed  and  climb- 
ing trials  shall  be  as  agreed  upon. 

Maneuvering  on  the  Surface 

Landing  —  The  aeroplane  shall  !«•  capable  of  being 
landed  down  wind  with  dead  motor  under  prescribed  con- 
ditions. Such  landing  shall  be  made  with  no  tendency 
of  the  aeroplane  to  spin  dangerously  or  to  turn  over  on 
its  nose. 

If  required,  the  aeroplane  shall  be  driven  along  the 
ground  in  a  straight  line  in  any  direction  <vith  res|>ect 
to  a  wind  of  a  velocity  between  15  and  20  m.p.h. 

Maneuvering  on  Water 

Seaworthiness  will  be  demonstrated  by  maneuvering 
the  surface  at  anchor,  adrift  and  under  way. 

The  purpose  of  such  trials  is  to  determine  staunchness. 
stability,  planing  power  and  longitudinal  and  directional 
control  under  varied  conditions  of  the  wind  ami  sea. 
representative  of  conditions  to  be  met  by  the  ty|x-  under 
consideration. 

In  a  calm,  with  full  load,  the  seaplane  shall  steer  read- 
ily. At  all  speeds  up  to  "  get  away  "  the  seaplane  shall 
respond  readily  to  the  controls.  It  shall  "  plane  "  at 
moderate  speed,  accelerate  rapidly,  and  get  away  within 
the  distance  specified.  It  shall  show  no  uncontrollable 
"  porpoising "  or  tendency  to  nose  over  at  any  speed. 
In.!,  r  this  condition  the  pro|x-llcr  should  be  free  from 
spray  and  broken  water. 

In   a   moderately    rough    sea    the   seaplane   shall    steer 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


270 

readily    in    all    directions    and    at    all    speeds.     It    shall 
"plane"   at   moderate   speed   and   without  undue       por- 
poising "  or  tendency  to  nose  over  under  any  condit 
with  the  wind  forward  of  the  beam. 

With  the  wind  abaft  the  beam  it  should  be  capable  ( 
running  slowly  or- at  moderate  speed  without  nosing  or 
without  undue  spray  or  broken  water  entering  the  pro- 
peller disk.     Down  wind  at  wind  speed  there  should 
sufficient  reserve  of  stability  to  prevent  nosing  over 

Headed  into  the  wind  there  should  be  no  marked  1 
ency  to  yaw. 


In  a  rough  sea  the  seaplane  shall  steer  readily  in  all 
directions  at  moderate  speed,  and  shall  steer  readily  at 
anv  speed  with  no  tendency  to  yaw  with  the  wind  any- 
where forward  of  either  beam.  It  should  be  able  to  get 
off  and  to  land  headed  approximately  into  the  wind  w.tl 
out  undue  punishment  to  the  seaplane  or  propellers. 

Adrift  or  riding  to  a  sea  anchor  or  to  a  ground  anch 
the  seaplane  should  not  take  any  dangerous  attitude  in  a 
calm,  moderately  rough  sea,  or  in  a  rough  sea. 


v  ii  API  I.H    VI 


METHOD  OF  SELECTION  OF  AN  AEROPLANE  WING  AS  TO  AREA  AND  SECTION 


Bv  .1.   A     it,,,  ,,,.    \|   \ 


This  ph-isc  of  design,  although  ,,f  „,.,..,,  imp,,,-!;,,,,.,.  ,f 
the  hitthest  etfici,  ncy  is  to  !«•  attained,  li.-is  loin;  |,,  ,.„ 

'••tl.      'I'll,-   first   reason    for  tins   was   (lie   lack   . 
pcrimental   data   on    which   i-,uii|i:ir:iti\i-   calculations   could 
be   IMS,,!.   ..,,„!    now    that    this   datn   is   plentiful   ami   trust 
worthv.  there  is  IIM  ,|iiick   -Hi, I  easy   way  t..  I, -ad  MM,-  to  t  In- 
correct <-<unl>iriat i,.n  ••!'  section  and  area  to  he  us,-,l. 

This  dith'cultx  aris.-s  fnuii  tin-  tact  that  Imtli  section 
and  area  ire  funrlioiis  of  ,  ai-li  other  and  also  of  tlu- 
weight,  power,  head  resistance  and  intended  purpose  of  the 
guchine. 

Aii\wa\.  an  aeroplane  is  pretty  sure  to  fly  satisfactorily 
•  rovidini:  t|,..lt  die  relation  between  tile  aliove  factors  IH- 
•hoseii  with  "  ii..,.<l  taste  "  or  with  nn  eye  on  the  nci^h- 
ior  s  machine.  |,,,t  there  is  ,-ver  the  doubt  that  the  machine 

not    at    its   liest  -     perhaps   a   ditT.-rent   curve   would  be 
•  Me         perhaps  a  little  less  surface  would  1),-  hettcr. 

One  of  the  co on  methods  now    used  in  making  this 

11  consists  in  picking  out  the   curve  of   highest  lift 


to   drift    ratio   available,  and    finding   tin-   area   by   mean* 
of  the  familiar  formula: 


. 
\\hrrr: 


II    =  Ihr  »riKht  ,,f  thr  mnrhlnr.  fully  loaded. 
Kf  =  thr  hlnhrst   lift   ,-.»•«;,  i,.,,t 

thr  low  »|ifrd  h«>|>«l  for  In  in.p  h. 
Ii  —  thr  «rc«  sought 


It  is  generally  assumed  that  the  se<tion  ehosen  is  the 
•  Ins  the  highest  lift  to  drift  ratio;  l.ut  no 
fair  lest  of  the  combination  is  had  until  the  characteristic 
curves  for  the  aeroplane  are  drawn.  Moreover,  to  draw 
such  curves  for  several  combinations  ,,f  section  and  arra 
would  require  a  great  deal  of  work  ami  then  the  com- 
parison would  lx-  rather  difficult. 

Vow    I    propose   to  demonstrate   a   method   which    I    have 
found   simple  and  satisfactory. 

In    general,    the    problem    presents    itself    as    follows: 
Specifications  require  a  certain  climb,  speed  range,  and 


' 


##>//>, 


tj 


J.H  iwrwi'    »  i 


I  ! 


t  I 


nil    i-lvirt- 


271 


of 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


272 

useful  load  to  be  carried  and  we  are  given  a  power  plant. 
There  are  seven  variables  to  be  considered,  namely: 

Kf,  /v  A,  r,  S,  V,  W. 
These  are  related  by  simple  expressions: 
T  =  A       1' 


1  1  to  allow  for  the  greater  efficiency  of  large  planes 
moving  at  high  speed.  We  can  also  multiply  the  area  by 
1  08  to  allow  for  the  greater  efficiency  of  the  aspect  ratios 
commonly  used.  Finally  A,  being  affected  by  interfer- 
ence, can  be  multiplied  by  .1),  the  equations  thus  corrected 
become :  \y 


Where  Kx  —  c°c        inriirinary  square  plate  whose  air 

figteMe °WOttld  be  equal  to  that  of  all  the  struc- 
tural parts  of  the  machine,  or  to  the  pa. 
sistance. 
K    =  The  coefficient  for  A 

sq.  ft.  X  m.p.h.- 

—  nm-^ft  — ~" — 

His. 

P    =  The  power  available  in  Ib.  miles  per  nr. 

V,  S,  W,  A"B  as  above 
From  which  we  get  by  transposition  and  cancelation : 


It  now  becomes  necessary  to  apply  to  these  equations 
the  factors  that  will  make  them  yield  results  in  terms  of 
the  desired  units  and  those  that  will  compensate  for  the 
following:  Aspect  ratio,  reduction  of  size  and  wind 
velocity,  interference  or  biplane  effect. 

All  possible  care  must  be  exercised  in  selecting  these 
coefficients;  they  will  be  different  for  different  types  of 
machines  —  the'  following  are  not  chosen  with  any  type 
in  view.  Some  valuable  indications  of  these  coefficients 
may  be  found  in  Loening's  "  Military  Aeroplanes  "  and 
in  Eiffel's  books. 

Mr.  Eiffel  recommends  that  the  area  be  multiplied  by 


1.08  x  1.1  X  9  X 
KA 


K_=- 


-•     1.1  xi.osxsr-i    1.1  x  i.os  x«     LIB  -si- 
It  would  be  more  accurate  to  apply  these  corrections  toj 
the  characteristic  curves  of  the  wing  sections  tested;  how 
ever  the  errors  of  this  method  are   slight,  and  since 
same  error   is   introduced   in   all   cases,   the  value   of  thisj 
method  is  not  impaired  for  purposes  of  comparison. 

Consider  the  graph  of  these  equations,  K,  being  plotted 
against  Ka  for  various  values  of  V  and  for  assumed  co. 
stant  values  of  -S,  W,  P  and  A. 

Note  that  these  equations  give  the  value  of  A,  neceitart 
to  flv  and  the  values  of  X,  available  at  various  velocit 
Note  also  that  the  effect  of  the   second  term   of 
equation  is  merely  to  subtract  a  constant  amount  from  tl 
K.  which  would  be  available  were  there  no  head  resistance 
This  amount  depends  only  on  A  and  S  and  its  value  is  real 
on  the  X,  scale  of  the  diagram.     The  effect  of  this  term 
is  then  to  displace  the  origin  of  the  plot  to  the  right  alon| 
the  A*  axis.      In  order  that  this  origin  be  easily  locat 
for   any  possible   value   of  A,  which   will   naturally   vai 
according  to  the  dimensions  of  the  machine,  and  for  t 
values  of  S  under  consideration,  a  set  of  lines  is  drawl 
as   shown   on    lower   left-hand  corner   of   wing  select* 


CH/jftT    rOR   THE     PET£Rr-IINRriON^  or  .  Jj^j;("':"SS'"'rl  CHKRT     FOR 

I  '• ' 

•«M»j-- 


—ro\,     7V>  eo" 


90   v        too 
•a.*.  »«*• 


AVinr   selection   diagram   calculation   charts    used 


to    facilitate    computation   of   coefficients   and   calibration   scale   used   to   gra| 
diagram 


MFTH01)  OF  SFFFCTION    OF   AN    A  FI{()1M..\  \  F   \\l\c. 


278 


agram.    from    which    th<-    valm  origin    thus 

1  .  1  '  •  x 

H-atcd   fur  any  given  Conditions.      I'sing  this   in  w    origin 

,  values  remain  as  tiny   were.  but  tin-  new    A      v  ili;.  -    in 

HIT  that  rrmniii  to  drive  tin-  wings  alone  through  tin     nr 

\"»    consider   tin-    |»i|:ir   curvis    nl    certain    tested    wing 

ctions;   these  curves   tirst   il.  -vised  b\    Mr.    l.illil   s,  em  to 

c  by   far  tin-  most   ingi  -nioiis  method  of  represent  in};  the 

••  ri^tics  of  a   win.;  MI  linn,  anil    I    wonilrr   why   their 

has    not    lieen    more    widely    adopted    in    this    eonntry. 

olar    curvi  -s    can    lie    den\ed.    however.    from    anv     other 

•i-ristie  eiir\es  available.  nr  translated  to  Ih.    i|. 
•  if  units  and   si/.e   from   tun  inn  polar  curves. 

that    these   eurves    give    the    A',    rfijuirrtl    by    tin- 
i-tion  to  nio\e  through  the  air  nt  various  angles  and  tin 
av.iilal  le    with    tin-    section    if    it    is    made    to    travel    at 
rioiis   incidences. 
Then   recalling  the   matter  on   page    I- 

lie        A      rripiireil        A 
lil.iMi  --  A"v  rr«|iiirr«l  =  A^  excess 
A       .  -         -   X  AV-  =  Kxccsx    power 

I  I  I  MCM    liftinp  capacity.  extra   load  which 

ennlil   have  lirrn  cnrrii-d. 


=  %  excess  power 


h'  100 

—  —  -  rr-r-. 
A     available 

e\i-ess  X  100 

=  %  excess  lifting  capacity. 


A^  nvniliililr 

Tin  si  \  ilues  as  well  as  the  speed  ranges,  can  be  ob- 
imd  easilx  for  se\eral  combinations  of  section  and  area 
superposing  polar  curves  and  the  diagram,  several 
amples  of  which  an  ^i\en  lati-r. 

It  is  i\id'-nt  that  the  above  excesses  arc  the  horizontal 
--rtieal  inten-epts  between  the  selection  curve  nnd 
e  polar  curve  and  when  these  excesses  are  «ero  we  have 
e  limits  of  Hight  range. 

\\  .  can  at  once  proeecd  to  illustrate  the  melli.nl  by  an 
ample  : 

Let  U         wi  j.;ht  of  maehiiie  complete  with  load  —  2500 

III'    —  120.  available  with  variable  efficiency. 

•niiig  various  values  for  V  we  can  tabulate  values 
r  K,  and  K,  for  values  of  S.  Let  us  try  250,  350  and 
0  sq.  ft.  Then  plot  the  curves  of  A"/-  in  function  of  A', 
ritini;  on  the  eurves  the  velocities  for  which  these  eoeffi- 
•nts  occur.  This  will  be  our  wing  selection  diagram. 
A  CIITM-  in  the  example  is  also  given  for  .S5O  sq.  ft. 
id  HUM)  Ibs.  to  stimulate  empty  gas  tanks,  in  order  to 
ow  the  conditions  of  flight  when  the  machine  is  light. 
The  peculiar  waves  in  these  eurves  are  due  to  the 
riable  efficiency  assumed  for  the  jMiwer  plant.  \Ve  know 
at  this  varies  from  zero  when  the  machine  is  standing 
ill  to  .1  maximum  value  when  the  machine  is  going  near 
highest  s|K*ed.  and  then  decreases  again.  If  the  effi- 
•ney  was  constant  these  curves  would  IH-  of  the  simple 
i: 

\  ri   '.•..  +  r  which  it  a  parabola. 

The  tabulation  and  diagram  follow: 

=  Assumed  efficiency  of  power  plant 
///•  X  K  =  Power  available. 

The  values  in  the  following  tabulation  can  be  obtained 
cans  of  a  slide  rule  or  by  the  use  of  the  accompanying 
kits. 


V  K        H.P.X.  F 


IM 


MM 

4.MO 

•    • 
• 


ZU.M 

.    • 


..  .. 

: 

.      -   .. 


n 

S 


744 

nc 


HI 


i 


84.  Ft. 
K 


For  4WS 

l.l«hl 
V  K 


J» 
40 

•n 

- 
• 

11" 


• 


•       ' 

. 
.-••Mil 

• 


v 

.mm 

•  •  • 


- 

.0004T7 


M 
•n 
7* 


II* 

. 


The  above  tabulation  could  be  further  improved  by 
letting  the  weight  change  for  each  value  of  area,  as  would 
be  the  cise  in  practice.  The  effect  of  this  would  In-  to 
bring  closer  together  the  ordinates  of  points  on  the  dia- 
gram. 

us  provide  ourselves  with  polar  curves  of  the  wing 
sections  that  we  wish  to  consider  and  draw  them  up  to 
the  same  stale  as  the  diagram.  For  ease  of  inspection, 
either  the  |«ilars  or  the  diagram  should  IK-  on  transparent 
paper  so  that  we  may  place  one  over  the  other  and  still 
see  both.  To  supply  the  example.  \  polars  of  to-day'* 
most  fashionable  curtcs  are  herewith  presented  with  the 
selection  diagram  superposed. 

With  the  alovc  material  at  hand  we  can  now  proceed 
to  select  our  wing.  The  observations  can  be  tabulated  as 
follows: 

T 


•La* 


J 


274 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


READINGS   FROM    WING  SECTION  DIAGRAM 


READINGS  PROM  WING  SECTION  DIAGRAM 


Section 

Area 

High  Sp'd 

Low  Sp'd 

Best  Glide 

Excess  Power           Section 

Area 

IIU-h  S|,M 

Low  Sp'd 

Host  Glide 

E\r<  ss   1'ow 

V        i 

V         i 

V       i  Gd.  % 

V       i     % 

V         i 

V          i 

V     iGd.  % 

V      i     % 

R.   A.   F., 
No.     6. 

250 
350F 
350L 
450 

83  314° 

77  214° 
77  114° 
Tl.r,  I'.. 

56.6  15%° 
48.3  16° 
42.2  17° 
42     16° 

60.5  8Vt°  12.5 
56.5  7%°  11.75 
49.5  7V4°  11.75 
53     6°      11.1 

65     8Vi°  22.2 
54     814°  32          Eiffel 
47.5  8%°  51           No.  36 
48     8°      39 

250 
350  F 
350  L 
450 

85      2%° 
79      1° 
80     -14° 
74       1£° 

59      1214° 
4SIL-  14 
41%  16° 
42.7  14° 

72     5°      13.1 
73      5°      12. 
54     5°      12. 
56      4.5°  11.25 

69      7°      15 
72     5°      22 
51     5%°  47 
53     614°  35 

Eiffel 
No.    32 

250 
350F 
350L 
•T-0 

Sli  1  --• 
83  3° 

87  iy«» 

8T  2° 

61     1314° 
50      15° 
43      17" 
44      15° 

77     6°      13. 
65      6°      11.75 
55.5  6°      11.75 
59     514°  11. 

75     7°      15 
63      614°  27.3        Eiffel 
55      6%°  47.4           No.  38 
55     614°  35 

250 
350F 
:J5UL 
450 

85     214° 
80     1° 

83      -V4° 
77      0° 

57      13° 
47.5  14° 
43      16° 
42      14° 

67      6%°  12.25 
56      6%°  11.25 
49.5  614°  11.25 
52      5%0  10.62 

67     7°      23 
56     7°      34 

19      7°      52 
50     6%°  40 

:4 


••  '    .'_/4iH 
jyn  ' 


POCAR   CURVE    FOR 
5ECTION   N«3Z  (EIFFEL) 
t—  Unrft   m    lb».  p«r  s<^. 

»'>*  aos.  Mumencal  .041 


:L:i£g 


§ 

. 

• 

. 

POLAR    CU 

...  ..„, 

7 

i      SECTION    N9 

3S 

// 
/;, 

'    i 

Unitj      ,n    Ib 

-m 

j      it  •  pfti-    mi. 

-W/r 

j       ' 

-      TRANSLATION 

I 

S'je  2.08.  Him 

j_| 

'  -I  ri.iir  nj_ 

i    ;-  i:--;  d  .-     J  -1- 

S  •  P0f  3«l. 


;:     POLAR  CURVE  FOB 
SECTION   N«38(EIFFEL) 

Units      IB    Ib5.    per  J<j. 
ft.    pftf.   hii.  p.hr. 


.    Units    m  ibs.  pe 
ft.  p«^.  nil.  p.  hr. 


MKTIIOI)  OF   SKLKCTION 


AN    .\I.KO1M..\.\K   \V1.\(, 


Tin-  selection  can  now   In-  made  according  to  the  results 
desired   with   proper  regard   for  tin-  slrinlur.il  ijunlitu  s  ,.! 
tin-   sections.       \\  e    will   thus   ha\e   selected,   in   a   sure   way. 
tin-   liest   wing    for  our   pnrposr.  .-mil   a   performance  curve 
can  now    In-   ilrawn.      This   iiM-tlioil  cnahlcs   us   to   visualise 
the   cll'cct    of   chances    in    the    \-iriou-.    factors.    MS    follows: 
1.   Since  K,.  is  not  ill  penili nt  on  /',  equal  velocities  at- 
ainalile   with    \arious   H.I'.,   for  a   i;ivcn  area  and  weight, 
will    lie   on   the    same    horizontal    line.   i.e..    if   our   powi  r    is 
the   alicissac   will    vary    proportionately 

A  iloi  s  not  ilepenil  on  /('  ei|iial  velocities  |nr 
area  and  power  will  lie  on  the  same  vertical  for 
nil  \alues  of  \V,  i.e.,  if  our  weight  is  changed  the  ordi- 
i.-ites  will  vary  proportionally. 


S.  A  Ungrnt  drawn  to  •  polar  from  the  origin  of  the 

diagram   will   show    |.\    its    point    of    cont-i.t    tin    \nluc   of 

INI  nli  nee  for  the  l>est  j-lulin^  nn^le,  on  the  snine  hortxontal 

i.l   Ih.    ,  ..rri -spoiidiiiu  spin),  (he  slope  i{i\es  the  value 

of  the  Ix-st   ^liiiing  gradient. 

I  Tin  httle  diagram  in  the  lower  part  shown  how 
parasiti  resistance  ciils  down  the  spied  and  CXCTM  |n>wer 
and  its  nlati\e  importance  on  m-iclum  s  of  largr  and  Miiall 
area. 

The  accuracy  of  the  |M-rform.ince  pr si  d  \>\  this 

method  d.-p.  mU  on  the  accuracy  with  which  the  head 
resistance,  power  avnilaltle  anil  the  currection  factors  II.-IM- 
l>een  determined.  The  accurate  selection  of  each  one  of 
thcuc  presents  a  prohlem  hy  it-  It 


CHAPTER  VII 


NOMOGRAPHIC  CHARTS  FOR  THE  AERIAL  PROPELLER 

Bv  S.  E.  SLOCUM,  Pn.D., 
Professor  of  Applied  Mechanics,  University  of  Cincinnati;  Member  S.  A.  E. 


In  discussing  propeller  performance  it  has  been  cus- 
tomary to  assume  that  the  power  absorbed  by  the  pro- 
peller varies  as  N*Dr>,  and  that  the  thrust  varies  as  N2D*, 
where  N  denotes  the  propeller  speed  in  revolutions  per 
minute  or  per  second,  and  D  is  its  diameter.  These  as- 
sumptions, however,  are  only  true  for  an  ideal  propeller; 
that  is,  one  which  is  perfectly  rigid  and  perfectly  sym- 
metrical. For  a  propeller  as  actually  constructed,  the 
law  governing  power  and  thrust  may  differ  materially 
from  the  above  theoretical  assumptions.  The  actual  laws 
governing  propeller  thrust  and  power  for  a  particular 
propeller  were  developed  directly  from  experimental  data 
obtained  by  M.  Eiffel  and  Captain  Dorand,  without  mak- 
ing any  theoretical  assumptions  whatever,  the  method  em- 
ployed being  the  standard  process  for  the  adjustment  of 
observations  by  the  method  of  Least  Squares.  The  re- 
sults showed  that  the  performance  of  a  given  propeller 
may  differ  materially  from  that  prescribed  by  theory  for 
an  ideal  propeller,  and  also  showed  how  experimental  data 
on  propellers  may  be  analyzed  on  its  own  merits,  inde- 
pendently of  all  dynamical  assumptions. 

As  long  as  the  whole  subject  of  propeller  performance 
was  in  the  experimental  stage,  it  was  doubtless  wise  to 
base  all  calculations  on  the  assumption  of  an  ideal,  pro- 
peller, as  it  gave  a  certain  uniformity  to  results.  At  pres- 
ent, however,  when  propeller  types  are  becoming  stand- 
ardized, it  certainly  permits  of  greater  refinement  in  de- 
sign to  determine  by  experiment  the  characteristics  of 
the  standard  types  of  propeller  adopted.  This  is  the 
method  followed  in  all  lines  of  engineering.  For  instance, 
the  performance  of  aviation  motors  is  determined  for  a 
given  type  of  motor  by  actual  test  of  this  type  and  not 
solely  from  the  principles  of  thermodynamics,  while  as 
another  example,  the  firing  data  for  a  long-range  gun 
are  based  on  experiments  made  on  this  particular  type  of 
gun  and  not  on  the  ideal  assumptions  of  a  perfect  pro- 
jectile fired  in  vacuo. 

Of  course  it  cannot  be  expected  that  general  formulas 
for  thrust  and  power  can  be  derived  which  will  apply  uni- 
versally to  all  types  of  propellers,  any  more  than  that  a 
gas  engine  power  formula  can  be  derived  which  will  apply 
accurately  to  all  types  of  motors.  It  is  perfectly  pos- 
sible, however,  to  derive  formulas  by  the  method  men- 
tioned above  which  will  apply  accurately  to  a  given  type 
of  propeller,  which  will  assist  materially  in  the  problem 
of  powering  aircraft,  that  is,  in  determining  the  most 
effective  combination  of  motor  and  propeller  for  a  given 
wing  and  fuselage  assembly. 

The  formulas  so  obtained,  however,  are  exponential,  and 
consequently  somewhat  difficult  to  use  in  their  algebraic 
form.  To  represent  graphically  the  various  combinations 

276 


of  quantities  involved,  M.  Eiffel  devised  what  he  called 

Polar  Logarithmic  Diagrams,"  which  constitute,  in  fact, 
a  very  ingenious  and  practical  application  of  vector  al- 
gebra. But  the  application,  as  well  as  the  theory  of  these 
diagrams,  is  rather  complicated,  while  the  results  depend 
in  part  at  least  on  determining  the  intersection  of  lines 
which  meet  at  an  acute  angle,  and  such  points  of  inter- 
section are  liable  to  a  considerable  error  when  determined 
graphically. 

There  has  recently  come  into  use  another  means  for 
the  graphical  solution  of  exponential  formulas  which  is 
similar  in  principle  to  that  devised  by  M.  Eiffel  in  that 
it  depends  on  the  reduction  of  an  exponential  to  a  linear 
form  by  the  use  of  logarithms,  and  the  employment  of 
logarithmic  scales.  This  device  consists  in  the  construc- 
tion of  diagrams  called  nomographic  charts,  or  alignment 
charts,  from  which  the  required  results  may  be  obtained 
by  simply  connecting  the  points  representing  the  given 
data  by  straight  lines,  and  then  reading  off  the  intercepts 
on  the  proper  scale,  the  method  being  similar  to  that  of 
using  a  slide  rule. 

In  Plates  I  and  II  accompanying  this  article,  no  >- 
graphic  charts  are  shown  which  represent  the  formulas 
for  thrust  and  power  of  the  aerial  propeller  as  previously 
derived  by  the  writer  in  the  references  given  above. 
These  charts,  of  course,  are  not  universal,  as  they  simply 
represent  the  performance  of  a  particular  propeller,  but 
similar  charts  differing  only  very  slightly  from  these 
may  be  constructed  for  any  standard  type  of  propeller, 
and  their  use  will  facilitate  calculations  on  this  propeller 
to  the  same  extent  that  the  use  of  the  ordinary  slide  rule 
simplifies  arithmetical  calculations. 

It  may  be  noted  that  the  effect  of  varying  the  ex- 
ponents of  N  and  D  will  be  to  move  the  intersection  axes 
slightly  to  one  side.  For  instance,  if  we  follow  the 
theoretical  assumption  that  the  thrust  varies  as  A'J7)4, 
the  intersection  axis  on  the  thrust  chart  will  be  moved 
slightly  to  the  right  of  the  position  shown;  while  sim- 
ilarly on  the  power  chart,  the  assumption  of  N3D'>  will 
also  move  the  intersection  axis  slightly  to  the  right.  Like- 
wise any  change  in  the  quadratic  terms  involved  in  these 
formulas  will  affect  the  relative  location  of  the  points  on 

V 

the  scale  giving  the  ratio  —  — ,  and  in  this  way  change  the 

ND 

readings  on  the  horsepower  and  thrust  scales.  Except  for 
such  shifting  of  the  intersection  axes  and  changes  in  the 
graduation  of  the  various  scales,  the  nomographic  charts 
will  be  exactly  similar  in  form  for  all  types  of  propellersj 
Having  determined  the  thrust  and  power  for  a  given 
propeller,  the  torque  and  efficiency  are  easily  found.  Thus 


DIAMET 

Fee 
PROPELLOR  SPEED    N 

ER      D 
t 
—  * 

—  J 
-4 

—  « 
—  7 
—  4 

bx 

Eumpl*   of  .,.|.lir.uon   of  rh.rt.     SnppOM 
X                 (t      |.ro|*ll,r   M««l    X  =  1400    r  p  m.  mtt 

130  fl    «w.     Tb»a  =  .60 

O                  Draw   •   line   Joining  UM  point  D  -  H    oith 
—                 UM  IntorMcUon  *>U  In  Uw  point  A       .li.in   i 

$                lot   =  .60.     Tb»   IntcTMrtlon   of   Ihw   I 

0                          M' 
K»l»  (im  300   II  I*    «|.|.ruiin»u>ly.               p 

ki 

HORSC   POWER 

—  s 

-to 
-30 

—  fa 
-_—  ^^^ 

A                   JOO 
—  4OO 

POWER 

—  /o«o                                                     FOR 

AERIAL    P 

t    iliimrirr    I>  —  « 
,|i.«.,    lini-ar   vrlocity    V  = 

Hi.'    iMiint   N  -  36.    rullinc 
u-   ,...,,,!   A   with  tin-  |Kilnt 

nr   with   thr   bone   powrr 

ATI°  jTO 

-1.00 

-AS 

-JOO 

-Jf 

-.70 
-J0f 

-40 

CHART 

THE 

=OPELLOR 

M- 

/wo 

/700 

AMU 
-/««o 

14- 

XJt- 

Zl- 

/JJO\ 
'JOO          >y 

It- 
11- 

\ 
//jo                       X 

-/OJO                                                 \^ 

•/too 
•9SO 

a- 

-esif 
1  —  O, 
-too 

-ISO 
-700 
-6SO 

NOMOGRAPH    OF  THE    FORMU 

-     t£,  O76  *-**   J".  /S             f                                -\r             /\f 

Rfi.                ip-N     D      ri  +  *4X.-« 

LA 

f] 

cum. 

•                                                            7S6  0  •  SSO 

-5.ET.5lo 

DIAMETE 
Ft 

PROPELLOR  SPEED  N 
Rcv./5*c        Re^MIn 

R     D 
et 

p 

—  s 

—s 
—  6 

1 

—II 
~—ut 

THRU5T    CHART 

FOR        THE 

„                AERIAL    PROPELLOR 

NOMOGRAPH    OF  THE    FORMULA 

jt» 

*7- 

««• 

-/7J-0 
-I7OO 

-tffo 
-/too 

-/.WO 

Z                                       '           30,000        L          VNW  J 

g 

^                                                                                                  RAT 
•0 

or 
u 

h                                          TMRUiT 
Z                                         Pounds 
—  10 

-90 

-4O 

-100 

~      4-OO 

Z—IOOO 

—4000 
^-JOOO 
^-4000 

Hj2.                          E./OOSO 

Ezcmpw  of  •pplication  of  chart.     Oir»n  D  =  8  ft,  N  =  1500  r.p.m.  =  I 
V        SS  ft    .«      Join  th»  |K»int  D  =  »  to  UM  point  N   -  35,  rutlm« 

•t  B.     Join   B  to  UM  point  =  .60.     Th«  Inur-clion  of  thl»  II 
ND 
UM  tbruit  teal*  ci»e»  F  =  TOO  lb>. 

•5.  &.olo< 

0  jfe 

-JO 

•Jl 
-40 

-.70 
-60 

^*** 

ti  r  r  • 
hi-   «n« 

»r    with 

um. 

0» 
•*.!- 
*/- 

-1*30             \. 

/•- 

/7- 
/«- 

-lisa 

-1100                                    \ 

\ 

-ioso                               X 

-/ooo 

-*JO 

/J- 

/a- 
//- 
/o  — 

-AM 
-400 

-WO 
-700 

—  600 

277 


PROPELLOR                              TORQUE  T 

-SPEED  N                                        Ft.Lbs.                       THRUST  F 

LINEAR    VELOCITY   V 

o          c                                         '°  — 

Lba. 

Fi/'Sec. 

<o       £                                    — 

—  IO 

O                                    /0 

1  1 

HORSE  POWER 

_ 

X. 

cr        a: 

—  /O 

2.0. 

rn                  -if.1,-1                                                       " 

oo  — 

40  — 



30 

o 

EFFICIENCY 

~                                                         -E 

20 

E"1*0 

y                                             Jte- 

Per  Cent. 

^ 

=- 

O 

—  /o 

X.S 

^AFOO                                                       /oo  

30 

=2 

U. 

-    ^\^ 

40 

^/OO 

U                                                         JO- 

- 

^X^                                  ,JOO  

—  SO 

- 

—  zo 

^                   300  — 

=- 

Zoo 

40- 

- 

*2  0  

^x^    40O  

—  

300 

rQ 

^^/oo 

— 

SO  — 

>4Op  

400 

— 

- 

^s 

^--5-00 

60  — 

40 

- 

,000^= 

^Ss 

B^ 

70— 

SO 

~       

EE  —      ~""T^^^^ 

C                                                                     o 

60 

— 

— 

~"==^—  _____ 

—  70 

- 

—  .300 

~--~^^       /oo  — 

30 
SO 

/S 

fZOOO  

_ 

4-00 

—  ^000 

^~^y/o^ 

—  /oo 

3000  

-  _ 

_ 

/i*=> 

_ 

-*ooo  — 

30OO 

/30- 
/40- 

JOOO-^ 

—  4000 

/SO  

— 

z= 

=—  tooo 

=- 

- 

/Mao—  = 

Er- 

^oo-— 

Ann 

=—/0  ooo 

ZX.O  — 

Example    of    application    of    chart.      1.  Given    N  =  1500    r.p.m.,    H.P.  := 

SUPPLEMENTARY    CHART 

200.     Join  these  points.      Intersection  of  this  line  with  torque  scale  gives 
torque  =  700  ft.  Ibs.     2.   Given  thrust  =  700  Ibs.,  lin.  vel.  =  120  ft  /sec 
H.P.  =  200.     Join  P  =  700  with  V  =  120.   intersecting  efficiency  axis  in 
point  C.     Join   this  point  C  with   H.P.  =  200,   and  prolong  to   intersect 
efficiency  scale  giving  efficiency  =  78%. 

FOR 

TORQUE  AND    EFFICIENCY 

Rrf  5 

O      '                                                             -5.E.^Jocum. 

Application  of  Chart.  Given  D  =  8 ;  N  =  1500 
r.i>.m.;  V  =  90  sec./hr.  Construction  shown,  as 
explained  on  Plates  1,  2  and  3,  gives  H.P  =  180; 
P  =  590  Ibs. ;  T  =  650  ft.  Ibs. ;  Eff.  =  76%. 


h 

"0 


— =v  0,000 


COMPLETE  NOMOGRAPHIC  CHART 

Firf  4.  FOR     THE 

AERIAL     PROPELLOR 


278 


NO.MOC.KAIMIU    CHANTS   1(>K   Till.     \l  K1AI.    1'IJOI'I   I   I   IK 


.•111(1 


I,.,,. 


\ 


••ilwork  I     \. 


Klliclcnev  =• 


:  work       .'.:>o h.p. 

whin    /•'  (Iciiiiti-s  tin-  |ini|irlliT  thrust,  .-mil  /'  is  tin-  s|M-cd 
of  tin-  plain-,  or  r.-l.itm    M  locity   of  tin-   wind   witli   r 
to   tin-    propt-llrr.      To   make    tin     <;raphic.-il    solution    com 
pli-tr,     howcicr.     DOmOgraphiC     chart-,     nriy     also     In 
stnicticl   tu   i;i\c   tori|in    anil   i  th'cicncy .   as   shown  on    Plate- 
Ill. 

These  charts  art-  presented  separately  in  Plates  I,  II 
-iii.l  III  tor  tin  sake  of  rh  arm-is,  and  an  example  of 
their  use  i--  shown  on  each. 

I  or  jiru-tii-al  purposes  it  is  more  eonvrnirnt  to  put  all 
tin-  .  Inrts  on  oni-  slu'i-t.  as  shown  on  Plate  I\  .  As  an 
i-xaniph-  of  its  use  it  may  Ix-  well  to  follow  through  the 
ron>' rurti. in  shown  on  Plate  IV.  In  this  example  we  are 


uiv.ii  pni|H-llrr  ili.-iiiii-ter  I)  =  8  ft.,  pn.pt  Her  speed 
AT=;I.,iiii  r  |,  I,,  j :,  r.p.s.;  linear  sprrd  /'  =  9O  miles 
|MT  hour  l.ij  ft  |H  r  Mft  1  irst  join  \  l.'.tMl  with 
D=K,  flitting  power  axis  in  A  and  thrust  axis  in  It. 

I  I 

BteH         —=.66,  join  . I  with  this  |Miiiit  on  the  .scale — 

\l>  M> 

for  powi-r.      Tin    iiitim  |<t  of  this  lim    with  the  |K)Wer  scale 

li.p.    —  18(1.      \r\t  join  H  witli  the  point  .tili  on  the 

/ 
scale for  thrust.      The  intercept  of  tins  Inn    with  the 

\/) 

thrust  •-,  Thrust  A'        .">!»>  Ihs.    Now  join  h  p.  =  180 

with  .V  ----  I.MMI.  Tin-  intercept  of  this  line  with  the  torque 
scale  gives  Torque  T  =  630  ft.  Ibs.  Lastly,  join  the 
point  Thrust  f=S90  with  the  point  /  •  on  the 

velocity  scale,  cutting  the  •  ilicn-ncy   axis  in  tin-  point   ('. 
.loin   this   point   ('   with  the   point    h.p.         I  HI).      The   int.  r 
i-ept    of    this    line    with    the    efficiency    scale    gives    Effi- 
ciency =  76  per  cent 


CHAPTER  VIII 


METHODS  USED  IN  FINDING  FUSELAGE  STRESSES 

BY  J.  A.  ROCHE,  M.  E.,  Aeronautical  Eng.,  U.  S.  A. 


Reasoning  Leading  to  Choice  of  Criterion  and  Methods 

Used  in  Finding  Stresses 

An   aeroplane   fuselage   is   a  structure    whose    function 
is  to  connect  the   wings,   landing  gear   and   tail   surface, 
of   the   machine;   hold   them    in   their   proper    respect, 
locations  and  transmit  the  stresses  which  hold  the  machine 
in  equilibrium,  in  the  air  and  on  the  ground   from  ea< 
one  of  these  parts  to  the  others.      Its  secondary  function 
is,  of  course,  to  house  the  engine,  aviator  and  accessor.es 
While  in  the  air,  the  fuselage  transmits   from  the  tail 
planes    to    the    wings    moments    which    are    necessary 
give    stability    or    to    neutralize    whatever    couples    may 
exist  due  to  center  of  pressure  and  thrust  line  locahon. 

In  normal  flight,   the   stresses   due   to  these  momenl 
are  slight,  but  in  exceptional  cases  such  as  in  recovenng 
from    a    vertical    dive,    these    moments    and    the 
thev  cause  are  large. 

It  may  seem  at  first  that  these  can  reach  enormous 
values  if  the  recovery  be  made  very  sharply  by  raising 
the  elevators  at  a  high  angle,  while  traveling  at  a  high 

rate  of  speed. 

It  has  been  measured  that  a  man  in  the  pilots  seat 
can  exert  a  push  or  a  pull  force  of  about  250  pounds. 
With  the  leverage  of  a  standard  "  Dep."  control,  the 
force  that  can  be  exerted  on  the  control  cables  is  about 
600  pounds  and  this  can  bring  about  a  reaction  of  400 
to  500  pounds  on  the  elevators  according  to  their  shape, 
on  which  depends  the  position  of  the  center  of  pressure 
behind  the  hinge. 

The  resultant  of  these  two  forces  is  as  shown  by  the 
above  figure,  and  this  resultant  can  be  used  as  a  basis 
for  a  stress  diagram  of  the  rear  end  of  the  structure. 

The  stress  diagram  yielded  is  of  the  simple  usual  type. 
Usually  no  attention  is  paid  to  stresses  in  the  rear  end 
of  the  fuselage  caused  by  landing  shock  and  the  front  end 
is  analyzed  by  itself  in  a  rather  crude  manner. 

The  object  of  the  following  is  to  investigate  the  latter 
condition  as  thoroughly  as  possible,  taking  into  account, 

Location  of  landing  gear, 

Location    of    center    of    gravity, 

Inertia  forces, 

Point  of  application  of  all  loads. 

As  a  machine  runs  along  the  ground  in  normal  position, 


the    reaction    force    applied    at    the    wheels,   being    equal 
and  coincident  with  the  resultant  of  the  loads  and  inert,; 
forces,  must  pass  through  the  axis  of  the  wheels  and  also 
through   the   center  of  gravity   of   the   machine, 
not   strictly   true,   because   other   forces   may   be    at   pis 
helping  the  machine,  namely:  airloads  on  the  mam  pis 
and  other  surfaces;  however,  it  would  be  fair  to  assume 
that  the  roughness  of  the  ground  produced  a  force  equal 
to  the  inertia  forces.      If  the  rolling  friction  is  very  high 
and  the  machine  has  a  tendency  to  turn  her  nose,  the  t 
air  loads  must  act  down  to  keep  the  machine  in  equil.bm 
whereas  if  the  rolling  friction  is  too  low  the  tail  air  loads 
must  act  up  to  keep  the  machine  rolling  on  her  wheels 

In  the  latter  case,  the  machine   will   have   a   tendency 
to  porpoise;   in   the   former,   it   will   have   a   tendency   1 
nose  over,  but  it  seems  that  if  the  wheels  are  so  local 
that    the    resultant    of    the    weight    reaction    and    rolling 
friction  passes  through  the  center  of  gravity,  the  aeroplane 
will  then  be  stable  as  it  strikes  or  rolls  on   the   ground. 
It  is  true  that  the   rolling   friction   is   a   very   variable 
factor,   but   it   certainly   has    a    mean   value    and   we    cai 
assume  that  the  inertia  of  rotation  of  the  aeroplane  will 
take    care    of   most    variations    from    this    mean   value    of 
rolling  friction. 

It  is  not  advisable  to  assume  the  machine  landing  wit 
a  perfect  "  pancake  "  and  striking  with  wheels  and  skid 
together,  for  this  is  neither  the  worst  nor  the  usual  con- 
dition of  landing.  It  is  preferable  to  assume  the  machine 
landing  on  its  wheels  only  in  normal  horizontal  position 
and  with  tail  planes  neutral,  which  is  a  fair  mean  between 
the  possible  conditions  mentioned  above. 

The  stresses  found  can  be  those  due  to  the  normal 
loads  taking  no  account  of  shock ;  and  since  shock  would 
not  alter  the  direction  of  the  forces  but  only  their  magni- 
tude, the  stresses  for  any  condition  of  shock  can  IK- 
obtained  later  by  applying  a  proper  constant  to  the  normal 
stresses  or  by  changing  the  scale  of  the  stress  diagram. 
The  work  can  be  performed  according  to  the  following 

plan: 

1.   Draw  to  scale  the  fuselage  under  consideration  and 
mark   on   it   the   centers   of  gravity   of   the   various   loads 


280 


MKTHODS  I'SKl)   IN    FIXDIXt;    1  1  SKI  .\(. I.  STRESSES 


281 


which    it    must    carrx  :    label    r;ich    one    with    it-,    n  r 
weight.       Discompose   each    one   of   these    loads    .mil    apply 
propi-r   share    to  each   oin-   of   tin    joints   on    whirh    r 

I.    Draw    \i  rlical   and    hori/ontal    fiinirulnr   polygons   or 
two  polygons  at   an  angh    to  ,-  ich   olhrr.       The  intrrsr.-lioii 
of    tlu-ir    resultants    gi\es    tin-    position    of    tin-    <•<  nl 
gr.iv  ity    of    tin     system. 

Draw   reaction  force  passing  thro<  Mills  found 

and    center   of   axh  .   make    all    load    Motors    parallel    to    it. 
J.    Draw    stress   diagram,    closure    will    In-    considered   as 
l-hrrk    on    the    work. 

i  rach  inrinlirr  according  to  tin-  stress  it  carries, 
taking    bending    or    Ir.inswrse    for,,  ,    hitii    account.       I  ..r 
tin-    portion    of    a    strut    In-low     the    point    of    application 
of   the    load   add   to   (In-   direct    stress   shown   by    the   stress 
•n   tin     portion   of   that    load    which   had   been   consul 
ere, I  .-is  applied  at  'In-  lower  end.      For  the  upper  portion, 
deduct  the  portion  of  the  load  which  had  been  consul,  re, I 
•pplied    to   the    upper   <  nd. 

It  was  admitted  in  step  5  that  the  stress  diagram 
was  not  the  final  operation  in  finding  the  close  value  of 
strr  ~,,  -  in  the  members  of  the  fuselage.  This  is  due  to 
ict  that  this  truss  is  loaded  internally.  Before 
starting  to  draw  the  diagram  the  forces  ha\e  been  dis 
Composed  in  a  definite  way.  we  must  now  correct  for  the 
effect  of  this  assumption  which  had  made  possible  the 
construction  of  the  stress  diagram. 

Step  ."•  indicates  bow  the  proper  correction  is  made 
for  the  stresses  in  the  vertical  struts.  The  reason  and 
method  are  ob\  ions.  A  similar  correction  should  also  l>e 
applied  in  the  hori/ontal  members.  It  is  clear  that  the 
various  pin  points  sustaining  a  load  will  partake  of  the 
hori/.ontal  component  of  the  force  due  to  the  inertia  of 
that  load.  Not  necessarily  in  the  inverse  ratio  of  their 
distanci  s  from  that  load,  but  in  a  way  depending  on  the 
riifidity  of  the  members  through  which  this  load  is  con- 
'I  to  them. 

Thus,  instead  of  having: 


The  resultant!!  of  these  systems  are  equal  in  all  re- 
spects; but  tin-  second,  more  correct  assumption  would 
cause  a  more  complicated  str.  s-  di  IUT.IIII.  which  would 
not  show  \irv  different  stresses  in  the  longeron*.  It 
seems  ijnite  proper  to  make  these  corrections  afterwards 
if  they  are  desired  at  all,  when  the  m<  tubers  havi 
.ned  and  their  degree  of  rigidity  is  known. 

In  the  ease  of  ohlicjiie  members,  both  a  vertical  and 
hori/ontal  correction  must  be  applied.  Tims,  in  spite 
of  the  efforts  of  this  method  to  give  close  accuracy,  there 
is  still  room  for  the  engineer  to  make  sunn-  corrections 
baaed  on  good  judgment,  but  these  corrections  mid  not 
IM-  made  in  most  ordinary  canes. 

The     present     example    illustrates    the    application    of 
the  method  proposed  here,  a  small  variable  angle  of  inei- 
ih  in  e  biplane  being  assumed.      The  apportioning  of  loads 
to  pin  points  is  done  as   follows: 
(I)    KntfiHf  and  Vroprllrr        I  Hi  Ibs. 

This  load  will  be  considered  us  applied  at  the  vertex 
of  a  small  triangular  truss  which  is  in  fact  supplied 
by  the  engine  crankcase.  Thus: 


(2)   Tank,,  Fuel  and  Oil. 

'  7 


Here  joint  a  must  take 


I 

20  X  U 


14.3  Ibs. 


14 

SOX  4 
b  must  take  -         —=5.7  Ibs. 

(3)    H'hrelt  —  *  t  Ibs. 

These  rest  direetlv  on  the  ground  and  impose  no  stresses 
If  strut  a  was  elastic  and  strut  6  rigid  we  would  have:      .      . 

(i)    H'inffi—  l-.'.'i  Ibs. 

As  in  the  ease  of  the  power  pant,  these  are  taken  as 
concentrated   at    the   joints   of   their   Mip|>orting   truss. 


a 


f 


/ 


(3)   Pilot—  160  Ibs. 

1  1  ;r,  +  0.3  n\  —  10  ;r,  —  1  1.3  n\  =  o 


These  moment  equations  show  that  we  have  an  indeter- 
minate case  as  could  be  expected,  since  there  is  more 
than  3  points  of  support,  all  we  can  do  '»»  to  eliminate 
one  of  the  terms  in  a  judicious  manner. 


282 


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14'-*- 


By  setting  for  example 

Wl=W2  X  16/14 

We   have   then  three   equations   containing   3   unknowns, 
as  follows: 

(1)  14  X  16  rFt  +  9.5  W3—  16  W2—  11.5  =  0 

14 

(2)  6V  16  Wz  +  6W2  —  16W3  —  15W4  =  Q 

14 

(3)  W,  16/14  +  JV2  +  Ws  +  Wt=  160 

~OW2  9.5  Ws  —  1 1.5  W4  =  0 
12.685  Wv  —  16  Ws  —  15  Wt  =  0 
2.142  W2  +  W3+W4=  160 


0  +  9.5  —11.5 
0  —16      —15 
16         1  1 

0  9.5  —11.5 

12.685  —16      —15 
2.142         1  1 


—22800  —29400 


—52200 


~-  53.8  Ibs. 


— 146  —  305  —123  —90.9 


16  X  53.8 
- 


=  61.5  Ibs. 


Check 


0  0  —11.5 

12.68  0  —15 

2.142     160  1 

—96.9 


—32.15  —  23300 


—96.9 


.  =  24.1  libs. 


0  9.5        0 

12.68       —16  0 

2.142          1        160    —19250 


—96.9 


—96.9 


•  =  19.9  Ibs. 


19.9  =  Wi 
24.1  =  Wa 
61.5  =  JPPj 

53.8  =  W2 
Total   159.3 


HORIZQNTHL    FuNICULRR  PoLV&ON 

-.OCATINb    CcMTEKOr  M/133  or  AfROPLflNF 


;.  1 . 


LOADING      DIAGRAM 

•Srrixv«>«     location  of  M*««t    (xJI)rd(rfd 
In  Sir, u  fUnft. 


IH     A  HOfttZONTAL   I  INC 


SCRLE  OF  DIMENSIONS  i  l*=20" 

FORCE      SC/JLE         |"=   100  Ibs 


/ 


VERTICBL  FUNICUIBR    PotxcoN 

Locflrtnft  CENTER  OF  MAIS  or  ACROPLANC 
IN   A  ICRTItni  lIMe  ^  ^ 

SCALE  or  DIMENSIONS  :    I  -.-  ZO 
FORCE    JCRLE:  »=lOOlbJ. 

J.«.f>Mhc    M.C.  C  U-   '«. 


STRESS 

SHOWING  LOCATION  am 

Or  GrlftvlIY 
Rt5utT«NT   REACTION 

STRESSES  m  ncnaeicj 
DIMENSION  Sem.i.-r=2o  w 
FORCE  SCflUE  :   |"=IM  i 


« 


MKTHODS    I   SKI)    IN    I  1M)1\(,    1  I  SKI    \(. I.   STKKSM   S 


288 


(6)   Tall  H'orkt  —  3()  11.-. 


7" 


_L 


At  tlii-.  point  it  is  interesting  to  study  the  retarding 
cll'cct  of  the  rolling  friction  which  lias  been  assumed. 
This  force  as  scaled  from  the  diagram  is 

F=  1  IT  ll.s. 

F—Ma 


since 


and 


~T~     i 


~~  ~  15-8 


mass 


/•'  1  1  A 

Hetardation  o  =  —  =  — ^— =  — 9.3 
.»/       — 147 


i 

also  a  =  —  =—  —  . 
a 


=  p—  =  —  9.8 

rfi 

and  J  f  </t»  =  J  —  U.S  </« 


Integrating  we  get  --  h  c  =  —  U.S  «  -j-  c 


to  <li  li  riiiiin  tin  \alne  nf  r  we  know  that 
in  the  case  of  a  landing  made  at  l<>  in.p.h.  at  the  instant 
of  first  contact  with  the  ground: 

V  =  58.6  ft./sec. 
and  5  =  0 

then—  -  =  c=17*0 

and  when  the  aeroplane  has  finally  come  to  the  V  =  O 
and 


and  this  figure  is  not  an  improhahle  one  for  the  machine 
•n  question,  anil  shows  a  capacity  on  the  part  of  the 
landing  gcnr  to  take  care  of  rather  rough  ground  without 
causing  the  machine  to  turn  on  its  nose.  If  this  figure 
u  :>  checked  on  the  nYld.  it  would  prove  that  the  rolling 
friction  has  been  correctly  assumed. 


CHAPTER  IX 


THEORY  OF  FLIGHT 

This  elementary  and  clear  definition  of  the  principles  of  flight  was  prepared  by  the  Aeroplane  Engineering  De- 
partment of  the  V  S.  Army,  from  lectures  delivered  at  the  Army  School  of  Military  Aeronautics  at  the  Ohio  State 
University.  These  lectures  were  given  by  Messrs.  H.  C.  Lord,  G.  T.  Standard,  and  W.  A.  Kmght. 

Investigating  wind  action  -  Constant  values  -  Studying  action  of  wind  -  Streamline  shapes -Head  resistance - 
Liff  drift  Md  angle  of  attack  -  Suction  on  top  of  plane  -  Center  of  pressure  -  Cambered  planes  -  Horizontal 
flight Engine  power  —  Power  to  climb  —  Stability. 


In  this  age  of  mechanical  flight  everyone  is  interested 
in  aeroplanes.  But  very  few  people,  however,  clearly 
grasp  the  underlying  principles.  The  theory  involved, 
nevertheless,  may  be  demonstrated  by  simple  experiments, 
so  that  the  reader  with  only  an  elementary  knowledge  of 
mathematics  and  mechanics  can  understand. 

The  simplest  principle  of  aeroplane  flight  may  be  dem- 
onstrated by  plunging  the  hand  in  water  and  trying  to 
move  it  horizontally,  after  first  slightly  inclining  the  palm 
so  as  to  meet,  or  attack,  the  fluid  at  a  small  angle.  It 
will  be  noticed  at  once  that  although  the  hand  remains 
very  nearly  horizontal,  and  though  it  is  moved  hori- 
zontally, the  water  exerts  upon  it  a  certain  amount  of 
pressure  directed  nearly  vertically  upwards  and  tending 
to  lift  the  hand.  This  is  a  fair  analogy  to  the  principle 
underlying  the  flight  of  an  aeroplane. 

The  wings  of  the  plane  are  set  at  a  small  angle,  and 
the  plane  is  pushed  or  pulled  through  the  air  by  the  pro- 
peller, which  receives  its  power  from  the  engine.  The 
action  of  the  air  on  the  wings,  inclined  at  an  angle,  tends 
to  lift  the  plane  just  as  the  action  of  the  water  on  the  hand, 
inclined  at  a  small  angle,  has  a  tendency  to  raise  the  hand 
out  of  the  water. 

Investigating  Wind  Action 

A  rough  form  of  apparatus  for  studying  laws  of  wind 
resistance  is  shown  in  Fig.  1.  The  arm  E  hinged  at  C 
carries  a  rectangular  plane  B.  The  adjustable  weight  D, 
supported  by  the  arm  F,  is  used  to  balance  the  pressure 
of  the  wind  from  the  blower  A.  The  pressure  exerted  on 
the  plane  B  can  then  be  measured  by  moving  the  weight  D 
along  the  arm  F  until  B  floats  with  the  wind. 

Professor  Langley,  in  another  experiment,  proved  that 
we  can  investigate  the  action  of  the  wind  upon  various 
forms  of  surfaces  as  well  by  directing  a  current  of  air 
of  known  velocity  against  the  surface  held  in  position, 
and  weighing  the  reactions,  as  we  can  by  forcing  the 
plane  itself  through  still  air.  The  special  apparatus  used 
was  mounted  on  the  end  of  a  revolving  arm  driven  by  a 
steam  engine  as  is  shown  in  Fig.  2.  The  chronograph, 
a  recording  instrument,  was  used  to  measure  the  velocity 
or  number  of  revolutions  of.  the  table  in  a  given  time. 

By  such  a  method  as  that  shown  in  Fig.  1,  and  that  of 
Professor  Langley,  it  is  easy  to  see  that  the  laws  of  pres- 


sure and  velocity  can  be  determined  readily.  Methods 
such  as  these  have  been  used  in  determining  that  the  iciiiil 
resistance  varies  as  the  square  of  the  velocity. 

In  other  words,  if  the  velocity  is  doubled  it  follows  that 
the  resistance  is  increased  four  times,  or  if  velocity  is  five 
times  as  great,  the  wind  resistance  is  twenty-five  times  as 
large. 


FIG.  1  —  Elementary  apparatus  for  studying  laws  of  wind  re- 
sistance 

Constant  Values 

It  would  therefore  seem  to  need  no  experimentation  to 
prove  that  if  we  increase  the  surface  B  (Fig.  1)  we  would 
increase  the  pressure  in  direct  proportion  to  the  increase 
in  surface  area.  Now  if  we  were  to  increase  both  the 
velocity  and  the  area  of  surface,  we  would  increase  the 
pressure  proportionally  to  the  product  of  the  square  of 
the  velocity  and  the  area  of  the  surface.  Thus  if  we 
were  to  raise  the  velocity  of  the  air  three  times,  the  re- 
sistance would  be  increased  nine  times,  and  if  we  then 
doubled  the  surface  we  would  double  the  resistance,  which 
has  already  been  increased  nine  times,  making  a  total  in- 
crease of  eighteenfold. 

There  is  still  another  factor  to  take  into  consideration 
in  calculating  wind  pressures,  and  that  is  the  shape  of  the 
surface.  To  take  that  into  account  we  must  use  what  is 
called  a  constant,  the  value  of  which  is  determined  by 
experiments  for  each  particular  shape  of  surface. 


284 


THKOHY   OF  KI.K.II  I 


-  1'rof.   I.murlry's   apparatus   for   invi-stijratinjr   wind   ac- 
tion on  various  forms  of  sun 

Tin-  following  explanation  will  enable  one  to  see  very 
•l.-arlv  tin-  meaning  of  the  term  constant  and  bow  its 
•able  i--  determined.  First  let  us  explain  the  term  formula 
which  is  merely  :i  si-ntence  tersely  expressed.  To  attempt 

0  make  a  study  of  flight  without   formulte  would  make  it 

iry  to  express  relations  between  <|uantities  in  long 
Mragraphs  of  words  that  could  more  readily  be  stated  in 
iiniple  equations.  Thus  if  it  were  desired  to  state  the 
•ule  that  the  quantity  A  multiplied  by  twiee  the  quantity 

1  i-  i  qua!  to  ('.  the  formula  representing  this  would  be: 

AX  2B  =  C 

Jach  letter  or  symbol  in  a  formula  represents  some  factor 
hat  is  substituted  when  its  value  is  known.  If  A  =  16, 
:nd  H=  I,  then  ('=128,  since  the  rule  interpreted 
eads:  Hi  X  8=  128. 

Derived  and  empirical  n/iiatiom. —  The  term  equation 
imply  means  that  the  quantities  on  one  side  of  the  equal 
iliii  are  equivalent  or  equal  to  the  quantities  on  the  other 
iide.  Equation*  are  of  two  kinds,  derived  and  empirical. 
\  derived  equation  is  susceptible  to  proof,  by  use  of  mathe- 
natical  processes.  An  empirical  equation  is  neither  de- 
ivcd  nor  proven.  It  is  merely  a  .statement  of  the  results 
f  experiment  regardless  of  mathematical  proof. 

In  many  branches  of  engineering,  empirical  formula-  arc 

•onstantly  used,  and  in  aviation  the  lack  of  a  satisfactory 

u-ory  of  air  flow  makes  empirical  formula?  based  on 

•xperimeiit  most  necessary.      Kmpirical  formula-  are  really 

mental  averages. 


Tin  i.  mi  .  "iiitant  can  now  be  fully  explained  and  it 
will  In  Men  IIOH  Ix-autifully  it  works  out  in  a  formula. 
It  is  often  found  necessary,  especially  in  an  rx|M-riiin  ntal 
tit  Id.  to  introduce  numerical  constants  to  balance  the  two 
sides  of  nn  equation.  For  example,  the  pressure  on  a  sur- 


1  PROJECTED 


In.     I  -  Illustrating 


of    term    "  projrctr<l    area  " 


face,  as  we  have  already  learned,  is  equal  to  a  constant 
times  the  projected  area  of  the  surface  (see  Fig.  .S)  times 
velocity  squar<il,  or  expressing  the  .same  quantities  in  a 
formula, 

P  =  KSV 

where  l>  =  Pressure  S=  Projected  surface  area 

K  =  Constant  V1  =  Velocity  squared 

The  exact  value  of  the  constant  K  for  any  surface  is 
determined  experimentally  by  wind  tunnel  tests.  So  val- 
uable have  wind  tunnels  proven  for  s  i.-h  determinations 
that  several  of  the  large  aeroplane  builders  now  have  in- 
stalled them  in  their  plants. 

In  solving  a  problem  it  might  !«•  known  that  the  pres- 
sure I'  \aries  as  the  area  of  the  surface  and  the  velocity 
squared,  but  we  could  not  express  this  relation  in  an 
equation  capable  of  solution  until  a  numerical  value  for 
K  is  determined  for  the  particular  sha|H-  subjected  to  Un- 
wind pressure,  such  as  the  shape  illustrated  in  Fig.  S. 
Kach  different  shape  of  surface  requires  a  different  value 
for  K,  which  can  be  determined  cxjx  rimcntally. 

The  majority  of  formula-  for  air  pressures  involve  con- 
stants, and  the  great  advance  in  designing  during  the  past 
two  years  may  lie  traced  directly  to  the  determinations  by 
the  aerodynamic  laboratories,  of  better  values  of  these 
constants,  for  use  in  empirical  formula-.  So  when  M. 
F.iffcl,  or  other  men  of  authority,  inform  us  that  the  con- 
stant K  for  a  flat  shape  is  .<><);(,  we  accept  the  value  just 
as  we  do  the  report  of  a  chemist  who  tells  us  the  compo- 
sition of  an  alloy. 

Parasite  Resistance 

A  picture  of  a  typical  aeroplane  is  shown  in  Fig.  5. 
Notice  that  all  the  struts,  wires,  landing  wheels  and  tin- 
fuselage  or  body  offer  resistance  to  passage  through  the 
air  —  a  resistance  which  must  be  overcome  by  the  engine. 
The  sum  total  of  the  separate  resistances  of  all  these 


I  i'..   V       K\|M-rim<*n 


HIT  lift  of  inclined 
rrnt 


Mirfnrr  in  air  cur- 


286 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


H 


FIG.  5  —  Curtiss  aeroplane,  showing  control  surfaces 


parts  is  called  the  parasite  resistance.  This  wastes  power 
and  so  all  such  parts  are  carefully  streamlined  wherever 
possible. 

Note  the  wings  or  aerofoils,  two  on  each  side,  one  above 
and  one  below,  and  at  the  rear  a  vertical  rudder  R  in 
front  of  which  is  a  vertical  fin  V,  and  the  horizontal  fin 
H,  the  back  part  of  which  can  be  turned  up  or  down  by 
the  pilot.  The  effect  of  this  is  to  cause  the  machine  to 
point  up  or  down  and  thus  change  the  angle  at  which  the 
relative  wind  strikes  the  aerofoils.  This  change,  as  we 
will  see,  has  much  to  do  with  the  flying  of  the  machine. 

Lift,  Drift  and  Angle  of  Attack 

Thus  far  we  have  found  a  lot  of  things  about  an  aero- 
plane which  would  tend  to  prevent  its  flying.  Now  let 
us  study  Fig.  4.  Here  we  have  a  plane  B  fastened  so 
that  it  makes  a  small  angle  with  the  direction  of  the  wind 
from  the  blower  A.  The  arm  is  hinged  at  C,  and  bal- 
anced by  the  weight  D,  so  that  when  the  movable  weight 
W  is  pushed  back  to  C  the  plane  B  will  be  slightly  too 
heavy.  When  the  blower  A  is  started  the  plane  B  in- 
stantly lifts  and  the  amount  of  this  lift  may  be  measured 
by  the  movable  weight  W.  If  we  replaced  this  model 


Fio.  6  —  Illustrating  how  lift  and  drift  result  from  the  moving 
of  an  inclined  surface  in  the  direction  of  arrows 


by  one  exactly  like  it  except  that  the  plane  B  makes  ; 
much  smaller  angle  with  the  relative  wind  we  would  fine 
that  the  movable  weight  W  would  have  to  be  much  nearei 
C  than  before.  This  simple  experiment  proves  the  exist 
ence  of  a  force  which  tends  to  lift  the  plane  and  furthei 
that  this  force  is  greater  as  the  angle  is  increased.  Tin; 
angle  is  called  the  angle  of  attack  that  the  plane  B  make: 
with  the  air  stream.  The  force  which  tends  to  raise  th( 
plane  is  called  the  lift,  and  evidently  its  value  must  de' 
pend  upon  the  profile  of  the  plane,  the  velocity  squared 
and  the  angle  of  attack. 

Besides  the  lift,  there  is  another  force  which  is  dui 
to  the  plane's  velocity  through  the  air,  called  the  drift 
This  force  is  due  to  the  fact  that  the  plane  itself  offers 
resistance  to  forward  motion  through  the  air.  In  Fig.  6 
A  represents  a  bubble  of  air,  BC  a  plane  moving  in  the 
direction  of  the  arrows.  Now  evidently  one  of  two  tilings 
must  happen.  Either  the  plane  must  force  the  bubble 
of  air  down  or  the  bubble  of  air  must  force  the  plane  up, 
This  resistance  that  the  bubble  of  air  offers  to  being  dis- 
placed, as  we  have  seen,  depends  upon  the  square  of  the 
velocity  with  which  it  is  forced  out  of  the  way.  The 
total  resistance  offered  by  the  bubble  to  the  movement  oi 
the  plane  may  be  represented  by  the  force  P  acting  al 
right  angles  to  the  surface  of  the  plane.  The  horizontal 
and  vertical  components  of  P  are  represented  by  D  and  L, 
respectively. 

If  we  were  to  let  the  air  on  the  surface  have  its  way.  il 
would  push  the  surface  upwards  in  the  direction  of  I 
and  backwards  in  the  direction  of  D  at  the  same  time. 

So  we  put  weight  on  the  surface,  enough  to  overcome 
the  force  L,  and  then  quite  logically  call  this  force  thj 
lift.  And  for  D,  we  push  against  it,  with  the  thrust  from 
a  propeller,  and  we  call  D  the  drift. 

This  simple  explanation  enables  us  at  once  to  state  the 
reason  why  flight  in  heavier-than-air  machines  is  possible. 
By  pushing  the  inclined  surface  into  the  air  with  a  hori- 
zontal force  D,  we  create  a  pressure  on  the  surface  equal 
to  P,  the  force  of  which  D  is  the  horizontal  component. 
But  by  doing  so  we  have  also  created  the  other  component 
L,  which  is  a  lifting  force,  capable  of  carrying  weights 
into  the  air. 


THKOHV   OF   FLIGHT 


•_'H7 


I'n..    '         \pparatiis    proving    existence   (if    lintli    lift    anil    drift 

Consideration  of  tin's  resolution  into  lift  and  drift  at 
OIKT  Indicate!  that  tin-  characteristics  to  be  sought  for  in 
a  surface  are  great  lift  with  a  very  small  drift,  so  that 
for  a  minimum  expenditure  of  power  a  maximum  load 
carrying  capacity  is  obtained. 

.lp /HI rut  11.1  nxi-d  to  prove  fiiitence  of  lift  and  drift. — 
An  apparatus  used  to  demonstrate  the  existence  of  these 
forces  is  shown  in  Fig.  ~.  The  inclined  plane  B  is  fast- 
ened to  the  arm  S  hinged  to  the  carriage  C  at  the  point 
F.  The  carriage  rests  on  a  glass  plate  I)  and  is  shielded 
from  the  wind  from  the  Mower  II  In  the  screen  K.  It 


I' I*..    s       I >r\ ice    for    measuring    comparative    air    pressures    IHI 
upper  and  lower  surfaces  of  an  inclined  plane 

u  found  that  when  the  blower  is  started  the  plane  B 
will  lift  and  the  carriage  C  moves  slowly  backward  carry- 
ing the  plane  with  it,  thus  proving  the  existence  of  lift 


and  drift.  The  screen  E  is  then  removed  and  it  is  found 
that  the  carriage  moves  away  very  rapidly,  thus  showing 
the  effect  of  the  added  head  resistance  due  to  the  carriage 

Its,  If. 

Suction  on  top  of  Plane 

Tin-  Hat  surface  is  seldom  used  for  the  aerofoils  of  an 
aeroplane.  The  following  illustrations  and  explanation 
will  help  to  show  the  reasons  for  not  using  it. 

The  plane  1'  (Fig.  8)  has  an  opening  at  ()  connected 
to  manometer  M.  while  on  the  under  side  is  a  similar  open- 
ing connected  to  the  manometer  X  through  the  rubber  tube 
T.  When  the  blower  is  started  the  manometer  .M  shows 
.suction  at  the  point  O  on  the  upper  side  of  the  plane  and 
\  shows  pressure  on  the  under  side  of  the  plane.  In 
other  words,  the  plane  is  not  only  blown  up,  but  it  is 
sucked  up  as  well. 

This  is  very  effectively  illustrated  by  n  still  simpler  ex- 
periment. Fig.  9  shows  the  plane  AB  of  heavy  card- 
board to  which  is  fastened  a  light  strip  of  paper  at  the 
point  A  and  left  free  at  the  point  C.  When  the  plain- 
is  placed  in  a  wind  blowing  in  the  direction  of  the  arrows 
the  paper  is  seen  to  be  drawn  up  to  the  position  AC'  away 
from  the  plane  AB. 

Experiments  at  Eiffel  Laboratory. —  Fig.  10  shows  the 
result  of  accurate  measurements  by  M.  F.iffel  of  the  suc- 
tion on  top  of  a  plane  and  the  pressure  underneath.  I-'ur- 


FIG.  9  —  Showing  suction  on  top  of  inclined  pi. UK-  when  exposed 
to  wind  current  in  direction  of  arrows 


^vast/re  Curve  kr 
iower •Surfoce 


I'n..    10 — Pressure    diagram    of    upper    and    lower    surfaces   of 
inclined   plane 

thermore,  F.iffel  has  shown  by  recent  experiments  that 
when  the  angle  of  incidence  of  a  flat  plane  is  low.  the 
value  of  the  suction  on  the  upper  surface  is  considerably 
more  than  that  of  the  pressure  on  the  under  surface. 
Thus  in  this  case  it  is  the  upper  side  of  the  plane  which 
contributes  most  towards  the  creation  of  the  lift,  a  func- 
tion increasing  as  the  angle  grows  smaller.  This  fact 
shows  that  the  profile  of  the  upper  surface  of  a  plane  li  is 
as  much,  if  not  more,  importance  from  the  standpoint  of 
the  value  of  lift  than  that  of  the  under  surface. 

Center  of  Pressure 

In  Fig.  1,  it  is  evident  that  the  wind's  force  on  the 
plane  B  could  be  entirely  replaced  by  a  single  force  act- 
ing at  the  center  of  the  plane.  The  fact  that  this  point 
would  In-  the  center  of  the  plane  is  due  to  the  fact  that 
the  wind  strikes  the  plane  absolutely  symmetrically.  On 
an  inclined  plane,  however,  the  action  of  the  wind  on 
the  front  or  advancing  edge  of  the  plane  is  different  from 
that  on  the  rear  or  trailing  edge  of  the  plane;  hence,  we 


•_>88 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


can  no  longer  say  that   the  center  of  pressure  is   at  the      change  the  position  of  the  center  of  gravity  by   placing 

a  small  lead  weight  on  the  front  edge.  Then  if  the  cor- 
ners at  A  and  B,  Fig.  13,  are  turned  slightly  upwards 
while  the  whole  is  given  a  lateral  dihedral  angle  as  shown 


geometrical  center  of  the  plane. 

The  result  of  the  double  action  of  the  air-current  with 
pressure  below  and  suction  above,  both  unequally  dis- 
tributed, is  that  the  total  reaction  on  the  plane  is  ap- 
plied at  a  point  C  (Fig.  11)  nearer  to  the  leading  edge 
A  than  to  the  trailing  edge  B.  This  point  C  is  called  the 


fLeac/  Weight 


C 


Fio.  11  —  In  a  flat  plane,  center  of  pressure  C  moves  toward 
the  leading  edge  A  as  the  angle  of  incidence  becomes  smaller 

center  of  pressure  of  the  plane.  In  a  flat  plane,  C  moves 
toward  the  forward  edge  a<s  the  angle  of  incidence  becomes 
smaller,  until  when  the  angle  is  zero  it  reaches  the  point  A. 
The  curve,  Fig.  12,  shows  the  position  of  the  center  of 
pressure  on  a  flat  plane  for  different  angles  of  attack. 
It  will  be  noticed  that  from  15  deg.  to  0  deg.  the  center 
of  pressure  moves  very  rapidly  towards  the  front  of  the 
plane  A.  The  wind  is  supposed  to  be  blowing  from  the 
right  in  a  direction  perpendicular  to  AB.  Aeroplanes  al- 
most never  fly  with  an  angle  of  attack  greater  than  13 
deg.  This  change  in  position  of  the  center  of  pressure 


Fio.    12 


BS/J 

30° 

— Location   of   center   of   pressure   on   flat   surface    for 
various  angles  of  attack 


very  easily  can  be  proven  by  a  well-known  and  very 
simple  experiment.  If  we  take  a  strip  of  light  card- 
board about  8  in.  long  by  1  1/2  in-  wide  we  know  that  the 
center  of  gravity  will  pass  through  the  geometrical  center. 
Now  if  we  were  to  project  this  through  the  air  in  a  hori- 
zontal position  with  the  long  side  forward,  the  center  of 
pressure  being  at  the  front  end  and  acting  upwards, 
while  the  weight  at  the  center  of  gravity  acts  downwards, 
a  couple  would  be  produced  causing  the  plane  to  rotate 
witli  the  advancing  edge  going  up.  This  shows  that  the 
center  of  pressure  is  near  the  front  edge. 

We  cannot  change  the  center  of  pressure  but  we  can 


C 

FIG.  13  —  Center  of  pressure  located  close  to  forward  edge  of 
cardboard  strip  used  in  simple  experiment 

in  the  lower  part  of  Fig.  13,  the  plane  on  being  projected 
in  the  air  is  seen  to  glide  almost  perfectly.  A  little  prac- 
tice is  necessary  in  adjusting1  the  weight. 

Figs.    14  and   15   show   pressures   and   the  path   of   the 


FIG.  14  —  Pressure  diagram  for  upper  and  lower  faces  of  curved 
surface  with  inclined  chord.     Compare  with   Fig.   10 


D'recf/on  of 
Wind 


Fio.  15  —  Location  of  center  of  pressure  on  a  curved  surface  at 
various  angles  of  attack.     Compare  with   Fig.  12 

center  of  pressure  for  a  curved  surface.  It  will  be  noted 
first  how  greatly  the  suction  effect  on  the  top  of  the  plane 
has  been  increased,  and  that  from  zero  to  15  deg.  (see 
Fig.  15)  the  center  of  pressure  moves  in  exactly  the  re- 
verse direction  from  the  way  it  does  in  a  flat  plane.  This 


TIIKOKY   OF   1  I.KiHT 


latter  cfl'cct   has  .-i   i  cry   iiiiport:iiit   bearing  when  wr  conic 
to  stability. 

Cambered  Planes 

1'i^'.  lii  IN  I  roiiiili  sketch  i>t'  wli.it  our  might  call  :i  typ- 
ir:il  win-;  section.  Noli-  tin-  difference  in  profile  |.. 
tlir  top  anil  liottoin  surface,.  Tlir  i-lmril  max  In  ilrliiiul 
as  tlir  straight  lim-  whirh  is  tangent  to  tlir  unilrr  surface 
of  tlir  arrnfuil  si-rtinii,  front  ainl  rrar.  and  the  aiiifle  of 
attai-k  as  tin  angle  hrtwrrn  tin  rrlatiir  wind  anil  the 
rliord  ot  tin  aerofoil.  We  may  «rile  tin-  following  sim- 
)ilc  expression  for  the  lift  and  the  drift: 

The  Lift  (10  =  kt8V» 
The  Drift  (D)  =  L/r. 


I  i...   !'•       Sketch    of 


typical   wing   section    with    aeronautical 
trrms  iiuiii  .iti-il 


'.  film  nt  k,  depends  upon  the  shape  of  the  aerofoil 

anil  the  angle  of  attack  and  must  be  determined  experi- 
mentally. The  <|iiantitv  r,  also  determined  experimen- 
tally, is  railed  the  lift-drift  ratio  and  measure-,  the  cffi- 
I'icncv  of  the  aerofoil. 


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AN&LC  OF  /NC/OENCe  Of  WIM6  CHORD 
MO.  17  — (  urv.s  .showing  values  of  kL  and  Lift/Drift  ratio  for 

a  typical  winp  section 


l-'i>t.  17  -nr,  two  rur\t,  fnr  m  m-rofnil  of  th,  sn-tioii 
shoHii.  Th.  tir,t  riirx.  j.i\rs  the  values  of  Ilir  i|ii.intit\ 
k,  for  different  nnjjles  of  attack,  while  tin  serond  ciirxc 
•In  \.ilur,  of  tin-  litt  drift  ratio. 

1  or  i  \ -niipli  .  sup|x>se  that  an  aeroplane  with  aerofoils 
of  the  Upr  shown,  lifting  surfaer  i!ii  si),  ft.,  is  Hying  at 
an  angle  of  attn.  k  of  II  drg.,  and  with  a  \elo»-ity  of  7<> 
m. p. h.  \\'lrit  will  l.c  the  lift  and  the  drift  ? 

I'roni  the  eh.-irt.  Fig.  17.  we  nnd  that  for  this  t\p.  of 
plan,  and  angle  of  attack  kL  (UMIiiH  and  r  —  II,  h.  nee. 

L  =  k.  SVJ  =  O.OOJ8  X«OX  (70)s  =  8>J  lb«. 

I 
D  = = =73  II*. 

r  11 

If  now  we  elian^r  the  angle  of  attack  to  ;fl  .,  d<  ^..  krep- 
illg  tile  surface  and  velocity  the  same,  \vr  tind  from  the 

ehart  that  kL  =  0.0014  and  T=-  18.5,  h<  D 


Horizontal  Flight 

For  horizontal  flight  the  lift  produced  Ity  the  machine's 
velocity  must  nt  all  times  exactly  eijual  its  weight.  1  • 
if  the  lift  were  less  than  the  weight,  the  pl.-mc  would 
fall,  while  if  the  lift  were  greater  than  the  weight,  the 
machine  would  In-gin  to  climh.  \\'e  therefore  can  replace 
the  lift  l.y  the  weight  \V.  Then  we  would  have  for  hori- 
zontal flight : 

Weight    (\V)         k.  M 

and  the  drift  (D)  =\\    r 

For   example,   a   given    aeroplane    weigh,    (with    load ) 
IK(K)    ll>s.      Its   aerofoils   arc   of   the   type   illustrated   and 
the   lifting  surface   i,    120  aq.   ft.     What   will    1»    it,    v. 
locity    for   horizontal    flight   at   an   angle  of  attack   of    12 
•leg.  ? 

From  the  ehart,  Fig.  17.  we  find  that  for  this  type 
of  plain-  and  angle  of  attaek.  kL=  <>.<>< i-J!),  whence,  ' 

I.  =  W  =  k  LSV=  or  1,800  =  0.00i9  X  1»  X  V» 


trnns|x>sinp,  V'  =  • 


ura 


.0029  X  120 
hrncr,  V=  V*,17i  =  7i  m.p.h. 

If   now   we   reduce   the   ani'le   of   attack   to   5  deg.,   the 
ehart.   Fig.    17.  shows  that  k,_  bcronn  s  (i. (Mil 7.1.   whence. 

1,800  =  0.00173  X  liO  X  \ 
transposing,    V»  =  - 


O.(l017i  X  HO 


HCIKT,  V  =  VH^'i  or  93  +  m.p.h. 

The  above  example  ill-istrates  this  important  principle 
that,  since  a  machine  in  horizontal  flight,  except  for  a 
slight  loss  due  to  consumption  of  gasolene,  main)  '.in,  a 
constant  weight  and  a  constant  surface  and  since  k  j_  for 

a  given  plane  depends  solely  upon  the  angle  of  attaek,  the 


290 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


velocity  for  horizontal  flight  is  completely  determined 
when  we  know  the  angle  of  attack.  Now  since  the  pilot 
can  control  the  angle  of  attack  by  means  of  his  elevators 
he  can  control  the  velocity  for  horizontal  flight. 

Fig.  18  shows  four  different  positions  of  the  plane  cor- 
responding to  four  different  angles  of  attack.  In  each 
case  the  machine  is  flying  horizontally,  though  at  first 
sight  one  might  think  that  in  position  4  the  machine  was 
climbing. 


FIG.  18 
FOUR  POSITIONS  FOR  FLIGHT 

(1)  Minimum  angle. —  This  is  the  smallest  angle  at  which  hori- 
zontal flight  can  be  maintained  for  a  given  power,  area  of  surface, 
and  total  weight.  The  minimum  angle  gives  the  maximum  hori- 
zontal flight  velocity  at  low  altitude.  Note  that  the  propeller 
axis  is  inclined  slightly  downwards  when  flying  at  this  angle., 

(-2)  Optimum  anyle. —  This  is  the  angle  at  which  the  lift-drift 
ratio  is  highest.  In  modern  airplanes  the  propeller  axis  is  gen- 
erally horizontal  at  the  optimum  angle,  as  shown  at  (^)  in  the 
above  figure.  Note  that  in  the  position  shown  the  velocity  of 
the  airplane  will  be  less  than  when  flying  at  the  minimum  angle. 
The  effective  area  of  wings  and  angle  of  incidence  for  the  opti- 
mum angle  are  such  as  to  secure  a  slight  climbing  tendency  at 
low  altitude. 

(3)  Rest   climbing   angle. —  This   angle   is   a   compromise   be- 
tween the  optimum  and  maximum  angles.     Modern  airplanes  are 
designed  with  a  compromise  between  climb  and  horizontal  veloc- 
ity.    At  this  angle  the  difference  between  the  power  developed 
and  the  power  required  is  a  maximum,  hence  the  best  climb  is 
obtained  at  this  angle.     See  Fig.  22. 

(4)  Maximum    angle. —  This    is    the    greatest    angle    at    which 
horizontal  flight  can  be  maintained  for  a  given  power,  area  of 
surface   and   total   weight.     If   the   angle   is   increased   over   this 
maximum,  the  lift  diminishes  and  the  machine  falls. 

It  would  seem  at  first  that  we  have  entirely  neglected 
the  engine,  especially  as  there  is  a  general  impression 
that  the  velocity  of  a  machine  depends  upon  the  power 
of  the  engine,  while  as  a  matter  of  fact  the  form  of  wing 
sections  together  with  the  plane's  dimensions  are  equally, 
if  not  more,  important.  In  the  preceding  discussion  we 
have  simply  assumed  that  the  engine  had  the  necessary 
power  to  maintain  the  plane  at  such  a  velocity  as  was 
determined  by  that  angle  of  attack  at  which  the  pilot 
drives  the  machine. 

Engine  Power 

The  power  of  any  engine  is  measured  by  the  velocity 
at  which  it  can  move  a  body  against  a  given  resistance, 
and  its  unit,  the  horsepower,  may  be  defined  as  the  power 
required  to  lift  one  pound  33,000  ft.  in  one  minute  or 
375  miles  in  one  hour,  or  the  power  required  to  lift  375 
pounds  one  mile  in  one  hour. 

We  must  therefore  multiply  the  total  resistance  offered 
to  the  aeroplane,  which  consists  of  the  drift  plus  the  para- 
site resistance  multiplied  by  the  velocity  of  the  machine, 


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Anq/e  of/ncic/ence 

FIG.  19 — Value  of  kL  and  Lift/Drift  ratio  for  a  given  niachin 

and  divide  the  result  by   375  to  get  the  horsepower  re 
quired.     Or,  written  as  a  formula: 

(Drift  +  Parasite  Resistance)  X  Velocity 

— —  =  Horsepower 
375 

From  the  above  expression  for  horsepower,  it  will  b 
noted  that  since  the  drift  for  a  given  machine  depend 
solely  upon  the  angle  of  attack,  and  the  parasite  resist 
ance  depends  upon  the  square  of  the  velocity,  which  i 
turn  depends  upon  the  angle  of  attack,  we  may  state  tha 
for  a  given  machine  with  its  load,  the  horsepower  is  com 
pletely  determined  when  we  know  the  angle  of  attack  a 
which  the  machine  flies. 

Fig.  19  corresponds  for  the  entire  machine  to  Fig.  1 
for  the  aerofoil  itself  and  gives  the  value  of  kL  for  a  give 

machine,  as  well  as  the  lift-drift  ratio. 

Fig.  20  gives  in  the  heavy  curve  the  power  require 
to  drive  the  machine  at  the  angles  of  attack  marked  o: 


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Fio.  20  —  Showing    power    required    at    different    angles,    als 
power  delivered 


TIIKOKY   OF   FLU. II  I 


the  riirvr.  which  correspond  to  tin-  sp. ed  in  miles  ]><-r 
hour  gixcn  at  tin-  bottom.  The  otlii-r  set  of  curxes.  four 
of  tin-Ill  dashed  .'iliil  one  ;i  li^ht  line,  unc  (lie  power  dc 
livercd  to  the  machine  by  the  engine  through  the  pro- 
pellcr.  The  latter  would  I  e  straight  hori/.ontal  lines  were 
it  not  for  the  tact  that  the  efficiency  of  the-  propeller  varies 
with  the  xdocity  of  the  aeroplane.  The  orclinates  as 
show  n  on  the  left  side  of  the  diagram  correspond  to 

horsepower. 

I. (I  us  .•(insider  the  case  where  the  cnuinc  is  making 
l.i ><>  r.p.ni.  It  will  lie  seen  that  if  the  pilot  changes  his 
clcxators  so  as  to  My  with  an  angle  of  attack  of  a  little 
less  than  1  detr.,  or  of  a  velocity  of  about  82.5  m.p.h..  he 


30" 


Fio.  .'I       Showing    rapid    changes    in    wind    velocity    in    short 
spaces  of  Him- 

will  be  using  every  particle  of  power  that  his  engine  can 
deliver  at  that  speed.  Any  slight  decrease  in  the  angle 
of  attack  will  cause  him  to  go  down  probably  in  a  nose 
dive.  As  he  increases  the  angle  of  attack  we  come  to  a 
point  where  the  distance  between  the  two  curves,  power 
delivered  and  power  required,  is  the  greatest.  Here  we 
will  have  the  greatest  excess  of  power  over  that  used  for 
horizontal  flight,  all  of  which  can  be  used  in  climbing, 
i  !  that  point  will  be  the  position  for  maximum  rate 

of  climb.  It  is  indicated  by  the  vertical  dash  line  marked 
m,,.,imum  rlimb  at  an  angle  of  attack  of  a  little  less  than 
6  deg.  or  a  velocity  of  a  little  over  55  m.p.h.  Increas- 
ing his  angle  of  attack  still  further,  or  at  about  8  deg., 
which  is  the  lowest  point  on  the  curve,  where  the  horse- 
power required  for  horizontal  flight  is  only  30,  we  get 


a  point  of  most  i  .•.inoinic.il  flight.  Then,  as  we  decrease 
the  angle  of  attack,  tin-  power  n  quired  rises  rapidly  until 
at  Hi  m.p.h.  the  two  curves  cross  again  and  any  iner.  IM 
in  the  angle  of  attack  would  cause  the  machine  to  stall  in 
I!K  sense  of  going  down,  which  might  take  the  form  of 
either  a  nosi-  div .  or  tail  slip.  It  is  well  to  compare  this 
with  Fig.  18. 

It  is  also  interesting  to  compare  this  with  l-'ig.  21, 
taken  from  I.angley's  Thr  Stored  Knrri/fi  of  the  It'inil, 
and  which  illustrates  the  rapid  changes  in  the  velocity 
of  the  wind  occurring  in  short  intervals  of  time.  The 
xertical  lines  represent  spaces  of  one  minute  and  the  hori- 
zontal lines  wind  speeds  differing  by  I  m.p.h.  It  will 
be  noticed  that  between  32  and  21  min.  the  wind  fell 
from  about  37  m.p.h.  to  12  m.p.h.  and  rose  again  to  :<H 
m.p.h.  On  account  of  the  momentum  of  the  aeroplane 
it  would  be  practically  impossible  for  its  actual  velocity 
to  change  with  anything  like  that  rapidity,  and  as  the 
lift  depends  upon  the  square  of  the  velocity  it  is  cxidint 
that  the  pilot  would  experience  a  series  of  "  humps  " 
when  the  velocity  increased,  and  momentary  drops  when 
the  velocity  decreased.  The  feeling  has  been  likened  to 
a  motor  boat  driving  rapidly  through  a  choppy  sea. 

Power  to  Climb 

Suppose  the  center  of  gravity  of  a  machine  be  moving 
in  the  direction  AB,  Fig.  22,  with  a  velocity  of  V  miles 


l-'iii.  -'-'     -Calculation  .of   power    required   to   climb 

per  hour.  The  horsepower  will  then  be  the  sum  of  two 
components,  viz.,  that  necessary  to  overcome  the  wind 
resistance,  as  already  given  for  horizontal  flight,  and  that 
necessary  to  lift  the  machine  through  the  distance  CH  in 
the  time  required  for  the  machine  to  travel  from  A  to  M. 
Now  if  AB  be  taken  to  represent  the  distance  the  mnchine 
travels  in  an  hour,  BC  would  then  represent  the  velocity 
of  climb.  The  power  consumed  in  climbing  is  equal  to 
the  product  of  the  weight  of  the  machine  in  pounds  by 
the  velocity  of  climb  in  miles  per  hour  divided  by  .•<?.''. 
Let  us  call  AB/BC  the  climbing  ratio  R  which  gives  us 
BC  =  AB/R  =  V/R.  We  will  have  then  the  power  ex- 
pended in  the  climb  alone  equal  to  WV/R,  and  the  total 
horsepower  becomes: 

(drift  +  parasite  resistance) V         \VV 
Horiepower  = 


174 


375  It 


The  case  of  special  interest  is  where  the  horsepower 
becomes  *ero.     This  is  the  condition  when  the  engine  is 
shut  off  on  a  glide. 
When, 

(drift  +  parasite  resUtanee)V         WV 

-(-  -     -  =  O, 

375  374  R 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


this  reduces  to 


W 


(drift  +  parasite  resistance) 


\zoo 


\/0 


f7-~. 


75 


•W  45  50  55  60   65   70    75   dO    85 
<Speec/  in  roi/e-s per hour 

Fio.  23  —  Showing   how   drift,   parasite    resistance    and    gliding 
motion  depend  upon  angle  of  attack 

It  should  be  noted  that  the  value  of  R  is  negative,  due 
to  the  fact  that  the  machine  is  gliding  toward  the  earth. 
Now  since  both  drift  and  parasite  resistance  depend  upon 
the  angle  of  attack,  the  gliding  velocity  and  slope  depend 
upon  the  angle  of  attack,  and  are  under  the  control  of 
the  pilot.  This  is  illustrated  in  Fig.  23. 

Stability 

One  of  the  most  important  considerations  in  an  aero- 
plane is  stability,  which  is  generally  considered  under 
three  (leadings,  viz.,  longitudinal,  lateral  and  directional. 

Lonr/itudinal  stability. —  This  stability  is  needed  to 
keep  the  aeroplane  from  pitching  nose  downward  or  tip- 
ping backward,  nose  up  and  tail  down,  whenever  a  gust 
or  eddy  is  encountered. 

Flat  surfaces  'are  longitudinally  stable  because,  as 
shown  in  Fig.  12,  the  center  of  pressure  moves  toward 
the  leading  edge  as  the  angle  of  incidence  is  decreased. 
Fig.  25  shows  four  positions  of  a  flat  surface  moving 
from  right  to  left.  Moving  horizontally  as  in  position  A 
the  center  of  pressure  is  at  the  leading  edge,  and  when  in 
the  vertical  position  D  the  center  of  pressure  coincides 
with  the  transverse  center  line  of  the  surface.  However, 
suppose  the  surface  to  be  moving  as  at  C  and  a  sudden 
gust  of  wind  tips  it  into  position  B  with  a  lesser  angle 
of  incidence.  Then  the  center  of  pressure  moves  for- 
ward, introducing  a  greater  moment  and  tending  to  force 
the  plane  back  into  its  original  position  C.  On  the  other 
hand,  if  the  surface  assumes  too  great  an  angle,  the  cen- 
ter of  pressure  moves  back  and  the  rear  is  forced  up, 
causing  the  surface  again  to  resume  its  original  position 
C.  Thus,  if  it  were  not  for  the  fact  that  the  flat  surface 
has  a  very  poor  ratio  of  lift  to  drift,  it  could  be  used  in 
aeroplanes  to  advantage,  due  to  this  inherent  longitudinal 
stability. 


Next  consider  Fig.  26,  giving  three  positions  of  a  cam- 
bered surface,  which  has  a  much  greater  lifting  efficiency 
than  a  flat  surface.  It  is  also  supposed  to  be  moving 
from  right  to  left.  In  position  C  the  center  of  pressure 
coincides  with  the  transverse  center  line.  Supposing  this 
surface  to  be  moving  in  attitude  B  with  the  center  of 
pressure  at  approximately  the  position  indicated.  If  it 
is  suddenly  tipped  into  position  A,  it  will  be  seen  that 
the  front  part  has  a  negative  angle  of  incidence,  which 
results  in  a  downward  pressure  on  this  portion.  The  cen- 
ter of  pressure  of  the  surface  being  the  resultant  of  all 
forces  acting,  it  is  obviously  affected  by  this  action  at  the 
front,  and  moves  backwards.  If  the  surface  is  tipped 
still  further,  the  backward  movement  of  the  center  of 
pressure  is  increased  and  therefore  there  is  still  less  tend- 
ency to  push  the  front  up,  when  such  a  tendency  would 
be  most  desirable.  On  the  other  hand  if  the  angle  of  in- 
cidence becomes  suddenly  greater  than  the  normal  posi- 
tion B,  the  pressure  on  the  front  edge  decreases  and  the 
resultant  center  of  pressure  moves  forward,  thus  tend- 
ing to  push  the  front  up  and  give  the  surface  a  still  greater 
angle  of  incidence. 

Therefore,  it  is  necessary  to  have  some  way  of  com- 
pensating for  this  instability  of  cambered  surfaces,  and 


Fara/M  to  Chord 
of  Lower  W/ny 


STAGGER  and DECA LA  GE  ~^ 


GAP' 


LA  TERAL  DIHEDRAL  anJ 3 PAN 


LONG/TUDINAL  D/HEDRAL 

FIG.  24 — Illustrating  meaning  of  some  aeronautical  terms 


TIIKOHV   or   1  l.KiHT 


298 


-    ' 


•  —  'Mir  rrntrr  nf  pressure  of  u  flat  plnnr  innvrs  forward 
us  the  angle  nf  inciilencr   i-  il 


.. 


.'li  Tin-  center  nf  pressure  nf  11  curxrd  .siirincc  mmrs 
forward  with  decreasing  miglcs  of  incidence  up  to  alxiut  I.'  di  ;;. 
Hi  luw  this  angle  it  re\erses  and  moves  toward  the  center  again. 


.'?  —  Illustrating  how  the  rear  surface  has  its  angle  of 

ineidi-nee    rriliiri'il    in    greater    proportion    than    does    the    front 
siiri'.uv  when  the  cnmliination  is  tip|M-d  downward. 

this  is  dour  hv  tin-  use  of  .-in  auxiliary  stal>ili/.ing  surface 
some  distance  hack  from  the  main  surface  and  set  at  a 
lesser  angle  of  incidence  than  the  main  surface.  Such  a 
stabilizer  is  a  necessary  feature  of  all  modern  aeroplanes. 
Fig.  27  shows  two  such  surfaces  in  tandem,  thus  forming 
an  elementary  aeroplane.  Consider  the  aeroplane  to  be 
traveling;  horizontally  with  the  angle  of  incidence  of  the 
main  surfaces  fi  dcg.  and  the  rear  one-third  of  this,  or  2 
(I.  ^.  Now  supposing  a  sudden  gust  pitches  the  plane  into 
some  such  position  as  shown  in  the  lower  part  of  the  dia- 
:n.  The  .ingle  of  incidence  of  both  surfaces  is  now 
reduced  say  1  deg.,  the  main  surface  being  at  a  '•  deg. 
angle  and  the  rear  surface  at  1  deg.  In  other  words, 
the  main  surface  has  lost  only  about  17  |HT  cent,  of  its 
angle  of  incidence,  whereas  the  stabilizer  has  lost  M  per 
cent.  Consequently  the  stabilizer  has  lost  more  of  its  lift 
than  the  main  surface,  and  it  therefore  must  fall  relative 
to  the  position  of  the  main  surface,  bringing  the  combina- 
tion back  into  normal  position  again.  On  the  other  hand, 
if  the  front  of  the  plane  is  suddenly  forced  up.  the  sta- 
bilizing surface  receives  a  relatively  greater  increase  in 
angle  of  incidence  than  the  main  surface,  hence  relatively 
greater  increase  in  lift,  pausing  the  back  end  of  the  plane 
to  !><•  brought  up  until  the  combination  again  is  normal. 

I.alrral  ttahility. —  This  stability  is  necessary  to  pre- 
vi nt  the  machine  from  rolling  about  its  horizontal  axis. 
It  is  difficult  to  secure,  but  is  often  promoted  by  having 
a  slight  lateral  dihedral  angle  between  the  upper  wing 
•urfaccs.  as  .shown  in  Fig.  28.  Should  the  aeroplane  sud- 


dcnly  be  tip|>cd  to  one  side,  in  the  position  shown  to  the 
right  of  the  diagram,  the  planes  on  the  (low  n  side  In  .  om< 
more   nearly   hori/ontal,   whereas,   those   on   the   other   side 
assume   an   angle   s'lll   greater   than   they   had   when   Hying 
normally.      Thus,  the  effective  projected  lifting  snrl 
tin    side   A   is   increased  and  that  on  side    M   is  deer 
bringing   the    plane    back    to    its    normal    lateral    position 
Other    features    arc    introduced    to    aid    lateral    staliility, 
such  as  "wash  in"  on  the  left  side  to  give  this  side  slightly 
more  lifting  ability   to  compensate   for   the   tori|iic  of  the 

propeller. 

Dirrclional  *tal>ility. —  Such  stability  aids  in  keeping 
the  plane  on  its  course.  In  order  to  prevent  yawing  with 
every  gust  of  wind,  the  vertical  tail  fins  present  on  nearly 
all  modern  planes  are  used.  Referring  to  Fig.  •.'!•  A.  sup 
pose  a  sudden  gust  of  wind  to  deflect  the  aeroplane  from 
its  normal  course  A  so  that  the  nose  points  off  the  course 
to  the  pilot's  left,  as  indicated  by  the  dotted  lines  in 
position  B.  This  swings  the  tail  around  to  the  right  so 
that  the  right  side  of  the  vertical  fin  presents  a  flat  sur- 
face to  the  wind  pressure  resulting  from  the  tendency  of 
the  machine  still  to  move  forward  in  the  direction  A,  due 
to  its  inertia,  even  though  it  is  temporarily  pointing  in 
direction  H.  A  moment  with  arm  r  is  thus  set  up.  which 
tends  to  swing  the  plane  back  on  its  vertical  axis  until 
the  fin  is  again  parallel  to  the  direction  of  the  relative 
wind.  The  action  is  similar  to  that  of  a  wind  vane,  tin- 
vertical  fin  of  which  always  keeps  it  [minting  in  the  di- 
rection of  the  wind. 


Fio.  29  —  Diagram  to  show  action  of  vertical  fin  in  preserving 
directional  stahilitv 


CHAPTER  X 


SHIPPING,  UNLOADING  AND  ASSEMBLING 

Shipping  instructions  —  Marking  boxes  —  Methods  of  shippping  —  Railroad  cars  used  —  Unloading  —  Method  of  load- 
ing on  truck  —  Tools  required  —  Unloading  from  truck  —  Unloading  uncrated  machines  —  Opening  boxes  —  As- 
sembling—  Fuselage  and  landing  gear  — Center  panel  and  wings. 


Shipping  instructions. —  Boxes  in  which  aeroplanes  or 
parts  thereof  are  shipped  should  be  marked  with  the  fol- 
lowing: 

Destination,  or  name  and  address  of  consignee  in  full. 

Sender's  name. 

Weight  of  box  (gross,  net  and  tare). 

Cubic  contents   (or  length,  width  and  height). 

Box  and  shipment  number. 

Hoisting  center. 

"  This  side  up." 

Methods  of  shipping  machines. —  Machines  are  shipped 
either  by  loading  in  a  railroad  car  without  crating,  or  by 
crating  in  two  boxes.  In  the  latter  case  the  wings,  cen- 
ter section  panel,  tail  surfaces,  landing  gear  and  propeller 
are  removed  from  the  fuselage,  and  the  fuselage,  landing 
gear,  propeller  and  radiator  are  packed  securely  in  the 
fuselage  box.  The  other  parts  are  packed  in  the  panel 
box.  All  aerofoil  sections  are  stood  on  their  entering 
edges  and  securely  padded  to  protect  their  coverings. 
Struts  are  stood  on  end. 

If  the  machine  is  not  to  be  crated  only  the  following 
parts  are  removed  —  wings,  center  section  panel,  tail  sur- 
faces and  propeller.  The  fuselage  is  loaded  into  the  rail- 
road car  and  allowed  to  rest  on  the  landing  gear.  The 
latter  should  be  blocked  up,  however,  to  take  the  load  off 
the  tires  of  the  landing  gear  wheels  and  off  the  shock 
absorbers.  The  fuselage  must  of  course  be  securely  fast- 
ened in  the  car  to  prevent  movement  in  any  direction. 
The  wings  and  other  separate  parts  are  crated  against 
the  sides  of  the  car.  The  wings  are  secured  with  their 
entering  wedges  down  and  carefully  padded  to  prevent 
damage. 

Railroad  cars  used  for  transportation.- —  If  possible 
open  end  or  automobile  cars  are  used  for  transportation 
of  aeroplanes.  Sometimes  with  crated  machines  gondola 
cars  are  used,  and  with  uncrated  machines,  ordinary  box 
cars  having  no  end  doors.  In  the  latter  case,  however, 
it  is  necessary  that  the  side  doors  of  the  railroad  car  be 
as  wide  as  possible,  to  allow  working  the  fuselage  in  and 
out  without  damage. 

For  transporting  machines  (either  crated  or  uncrated) 
from  the  railroad,  a  flat  top  truck  is  used.  If  the  truck 
is  short  it  will  be  necessary  to  use  a  trailer  to  support  the 
overhang  of  the  boxes. 

Unloading 

Method  of  loading  on  truck. —  Before  unloading  a  ma- 
chine, everything  in  the  railroad  car  should  be  inspected 

294 


for  loss  or  damage.  If  everything  is  O.  K.  proceed  with 
the  unloading,  but  if  any  loss  or  damage  is  discovered  re- 
port fully  at  once  to  the  receiving  officer  and  await  his 
instructions  before  doing  anything  further. 

The  tools  required  for  removal  of  aeroplane  boxes  from 
the  railroad  car  are:  1  axe  or  hatchet,  2  crow  bars,  6  or  8 
rollers  and  100  ft.  of  1  in.  rope. 

The  cleats  holding  the  boxes  to  the  car  floor  are  first 
removed  with  the  axe  and  crow  bars,  and  the  panel  box 
removed  from  the  car.  If  the  fuselage  box  is  not  marked 
to  show  which  is  the  front  end  it  should  be  lifted  slightly, 
if  possible,  first  at  one  end  and  then  at  the  other,  to  de- 
termine which  is  the  engine  end.  This  end,  being  the 
heavier,  should  come  out  first  if  possible. 

The  truck  is  backed  up  to  the  door  of  the  car,  rollers 
are  placed  under  the  fuselage  box  and  it  is  then  rolled 
out  onto  the  truck.  The  rope  is  now  used  to  fasten  the 
box  to  the  truck.  After  this  is  done  the  truck  is  moved 
forward  slowly  and  the  box  is  thus  pulled  out  of  the 
car.  If  a  trailer  is  to  be  used  it  should  be  placed  under 
the  box  before  the  latter  is  taken  all  the  way  out  of  the 
car. 

When  taking  the  fuselage  out  tail  end  first,  the  same 
methods  are  used,  except  that  the  light  end  is  blocked  up 
when  removed  from  the  car  and  a  truck  is  put  under  the 
heavy  end. 

When  moving  along  roads  care  should  be  taken  to  go 
slowly  over  rough  places,  tracks  and  bad  crossings.  It  is 
also  a  good  policy  to  have  a  man  on  each  side  of  the  box 
to  watch  the  lashings  and  see  that  nothing  comes  loose. 

Panel  Box 

The  wing  box  (or  panel  box)  is  removed  from  the  car 
in  the  same  manner  as  the  fuselage  box. 

Unloading  boxes  from  truck. —  For  this  work  2  planks 
about  2  in.  x  12  in.  x  12  ft.  long  should  be  used.  These 
should  be  fastened  to  the  end  of  the  truck  with  one  end 
resting  on  the  ground,  so  that  they  will  act  as  skids.  The 
tail  end  of  the  fuselage  box  is  depressed  until  it  rests  on 
the  ground,  then  by  moving  the  truck  forward  carefully 
the  box  will  slide  down  the  planks  onto  the  ground. 

Unloading  uncrated  machines. —  In  this  case  all  of  the 
smaller  parts  should  be  removed  first.  Then  the  cleats 
and  ropes  are  removed  which  hold  the  machine  in  the  car. 
Two  long  planks  are  placed  from  the  door  of  the  car  down 
to  the  ground  and  are  used  to  roll  the  machine  out  of  the 
car. 

Opening  boxes. —  A  screw  driver  and  bit  brace  should 


NU  r\I.()Al)IN(.    \\D  ASSEMBLING 


!><•  used  to  ri-moxc  tin  sen  -ws  in  the  tn|i.  sides  .uid  i -nils 
of  the  lxi\.  Tin-  top  i-  removed  tirst.  then  one  side.  AH 
smaller  parts  nt  tin  iii.-ifliinr  should  In-  t;ikrn  out.  after 
which  tin-  remaining  side  of  tin-  lm\  is  removed,  and  lastly 
tin  i  mis. 

/>  ^inl'liiii/  ii  in  in- lii  in-.  Tin-  landing  gear  shoidil  In- 
put on  first.  To  do  this  tin-  fuselage  must  In-  raised  hv 
our  of  t«o  ini-tliods.  Tin-  first  is  by  cliain  falls  or  Murk 
and  tackle.  Tin  ro|n-  slinu  should  In  passnl  iindrr  the 
engine  sill  just  to  (In-  rear  of  the  nose  plate.  Tin-  tail 
of  tin-  inai-liiin-  is  allowed  to  rest  on  tin-  tail  skid  while 
the  nose  is  raised.  The  second  method  is  by  shims  and 
blocking.  This  latter  method  is  the  most  common  hei-.-iuse 
chain  falls  are  not  always  a\  ail-iMc.  l-'.nutigli  Mocks 
.should  In-  secured  to  raise  the  fuselage  high  enough  to  slip 
the  1  -iiiilin^  year  underneath.  The  tail  is  tirst  raised  by 
•J  men  and  Mocks  are  placed  under  Station  5  or  the  rear 
wini;  section  strut.  The  blocking  must  be  directly  below 
the  strut  and  must  have  padding  upon  it.  Then  the  tail 
is  depressed  and  another  block  is  put  under  the  forward 
wing  strut.  This  operation  is  then  repeated  until  the 
fuselajjc  is  hitrh  enough  for  the  landing  gear  when  the  ma- 
i-liine  is  blocked  under  nose  and  tail  and  the  other  blocks 


tour  men  arc  all  that  xhould  br 

n-(|uircd  for  this  second  method. 

Assembling  Wing* 

r  the  landing  grar  is  nssemMi  d  the  center  s. 
pin.  I  should  be  attached  and  approximately  lined  up. 
Then  tin  wind's  ..,rt-  assembled.  There  are  two  methods 
for  il.,in-  this;  one  i*  to  put  on  the  top  plains,  place  sup 
purls  under  the  outer  edges,  then  put  in  struts  and  luwei 
planes  and  connect  up  the  wires.  The  other  method  is 
to  assemble  the  wings  completely  while  on  the  ground. 
\\  Mitts  are  sto»xl  on  their  entering  nine,  struts  are  put  in 
and  wires  tightened  up  to  hold  the  wing  irrtioiis  together. 
Then  tin-  wings  are  attached  to  fuselage  by  turning  them 
over  and  attaching  the  top  wing  tirst.  then  the  lower  wing. 
One  side  of  the  machine  must  IK-  sup|xirted  until  the  oppo- 
site set  of  wings  is  attached.  After  wings  arc  all  at- 
tached, then  the  tail  surfaces  should  be  assembled  to  the 
body.  The  horizontal  stabilizer  should  go  on  first,  then 
the  vertical  fin.  rudder  and  elevators  in  the  order  named. 
On  some  machines  the  elevators  will  have  to  be  put  on 
before  the  rudder.  After  everything  i*  assembled  the 
machine  is  put  in  alignment. 


CHAPTER  XI 


RIGGING 

Fuselage  —  Construction  —  Longerons  —  Struts  —  Fuselage     covering  —  Monococoque  —  Landing     gear  —  Struts  - 
Bridge  —  Axle  box  or  saddle  —  Axle  and  casing  —  Wheels  —  Tail    skid  —  Shock    absorber  —  Wing    skids  —  Pon- 
toons on  seaplanes  —  Flying  boat  hull  —  Wing  construction  —  Front   and   rear   spars  —  Ribs  —  Cap   strip  —  Nose 
strip  —  Stringers  —  Sidewalk  —  Struts  —  Wire  Bracing  —  Wing   covering  —  Dope  —  Inspection    windows  - 
wires  and  terminal  splices  —  Aircraft  wire  —  Strand  —  Aircraft    cord    or    cable  —  Terminals    and    splices  —  Solder 
ing  —  Turnbuckles  —  Locking  devices. 


Rigging  deals  with  the  erection,  alignment,  adjustment, 
repair  and  care  of  aeroplanes. 

Aeroplanes  are  of  light  skeleton  construction  with  parts 
largely  held  together  witli  adjustable  tie  wires,  hence  they 
easily  can  be  distorted  or  their  adjustment  ruined  by  care- 
less or  improper  rigging.  The  efficiency,  controllability, 
general  airworthiness  and  safety  of  machine  and  pilot 
therefore  depend  very  largely  upon  the  skill  and  con- 
scientiousness of  the  rigger. 

For  purposes  of  description  the  aeroplane  may  be  di- 
vided roughly  into  three  parts  (exclusive  of  the  power 
plant).  These  are  the  body  or  fuselage,  the  wings  or 
aerofoils  and  the  landing  gear. 

The  fuselage  is  the  main  structural  unit  of  the  aero- 
plane. It  provides  a  support  and  housing  for  the  power 
plant,  contains  the  cockpit  for  the  pilot,  and  the  instru- 
ments and  control  mechanism.  The  rear  end  of  the  fuse- 
lage carries  the  rudder,  elevators,  stabilizing  fins  and  the 
tail  skid.  The  wings  or  aerofoils  are  attached  to  the 
fuselage  through  suitable  hinged  connections  or  brackets 
and  the  fuselage  is  supported  by  the  wings  when  the  ma- 
chine is  in  the  air.  Conversely  the  wings  are  supported 
from  the  fuselage  when  the  aeroplane  is  on  the  ground, 
as  in  that  case  the  whole  weight  of  the  machine  is  sup- 
ported by  the  landing  gear  and  the  tail  skid,  both  of  which 
are  attached  under  the  fuselage. 

The  body  or  fuselage  is  of  trussed  construction,  a  form 
which  gives  great  strength  and  rigidity  for  a  given  weight 
of  material.  Parts  assembled  together  in  the  form  of  a 
truss  are  spoken  of  as  members.  Those  which  take  a 
thrust  only  are  called  compression  members,  while  those 
resisting  a  pull  are  known  as  tension  members. 

Other  members  may  be  either  tension  or  compression 
members,  depending  on  how  the  load  or  force  is  applied 
to  them  at  any  given  time.  There  are  also  members 
subject  to  a  shearing  stress  and  others  to  cross-bending 
or  compound  stresses. 

The  fuselage  is  usually  constructed  witli  four  main  lon- 
gitudinal members  running  the  full  length.  These  are 
called  longerons.  They  are  separated  at  intervals  by 
compression  members  termed  struts.  The  whole  struc- 
ture is  in  turn  tied  together  and  braced  by  means  of 
diagonal  wires,  fitted  with  turnbuckles  for  adjustment, 
which  go  under  the  general  name  of  wire  bracing  or 
stay  wires. 

Stay  wires  in  certain  parts  of  an  aeroplane  are  desig- 


296 


nated  as  flying,  ground,  drift,  anti-drift,  etc.  These  will 
be  considered  later. 

That  part  of  the  surface  of  the  fuselage  which  is 
bounded  by  two  struts  and  two  of  the  longerons  is  known 
as  a  panel.  The  points  at  which  the  struts  join  the 
longerons  are  called  panel  points  or  stations.  The  cu- 
bical space  enclosed  by  eight  struts  and  the  four  longerons 
is  called  a  bay.  Some  makers,  Curtiss  for  instance,  num- 
ber the  stations  in  the  fuselage  from  front  to  rear  call- 
ing the  extreme  front  station  No.  1.  Others,  such  as 
the  Standard,  number  these  stations  from  the  rear  toward 
the  front,  calling  the  tail  post  zero. 

The  longerons  are  made  of  well-seasoned,  straight- 
grained  ash*.  They  are  curved  inward  toward  the  front 
end  and  usually  terminate  in  a  stamped  steel  nose  plate. 
This  is  true  particularly  of  aeroplanes  equipped  with  en- 
gines of  the  revolving  cylinder  type.  The  nose  plate  is 
stamped  from  plate  steel  about  .10  in.  in  thickness.  This 
plate  not  only  ties  the  longerons  together  at  the  front  end 
of  the  fuselage,  but  supports  one  end  of  the  sills  on  which 
the  engine  rests.  In  some  types  of  planes  it  also  forms 
a  bracket  for  supporting  the  radiator.  In  other  types 
of  aeroplanes  the  longerons  may  terminate  at  the  front 
end  of  the  fuselage  in  an  open  frame  which  forms  the 
support  for  the  radiator  and  also  supports  the  front  ends 
of  the  engine  bearers  or  sills.  The  two  upper  and  the 
two  lower  longerons  are  brought  together  in  pairs  one 
above  the  other  at  the  rear  end  of  the  fuselage,  and  are 
joined  to  the  tail  post  or  vertical  hinge  post  on  which 
the  rudder  is  mounted. 

Lightened  Construction 

In  order  to  lighten  the  construction  of  the  fuselage  as 
much  as  possible,  the  rear  portions  of  the  longerons  are 
often  cut  out  to  an  I  section  and  spruce  is  often  substi- 
tuted for  ash  for  the  rear  half,  suitable  splices  strength- 
ened with  fish  plates  being  used  wherever  joints  are  made 
in  the  longerons.  It  is  possible  to  lighten  the  rear  por- 
tion of  the  fuselage  in  this  way  for  the  reason  that  this 
part  of  the  body  does  not  support  as  much  weight  or 
undergo  as  severe  stresses  as  the  forward  portion. 

In  a  machine  of  neutral  tail  lift  (one  in  which  the  rear 
horizontal  stabilizers  are  set  at  such  an  angle  that  they 
barely  sustain  the  weight  of  the  rear  portion  of  the  ma- 
chine when  flying  horizontally  in  the  air)  the  stresses  in 
the  longerons  are  exactly  the  opposite  when  the  machin 


RIGGING 


•-".'7 


Mum  inj;  priiicipul  piirt.s  of  fuwl«gr 


is  in  tli.  air  In  those  obtaining  on  the  ground.  \Vln-n  thr 
urn-bine  i,  .it  rest  mi  the  ground  it  is  supported  near  the 
front  ami  n  ar  .mis  of  the  fuselage  liy  the  landing  gear 
anil  the  tail  skid.  This  method  of  support  proiluees  ten- 
sion in  the  lower  longerons  and  compression  in  the  upper. 
When  in  tin-  air  the  niai-hine  is  supported  by  the  wings 
which  arc  attached  to  the  fuselage  at  the  center  whin 
ion.  The  system  of  supports,  trusses  and  stay  wires 
lictwccn  the  upper  and  lower  wings  transfers  most  of  the 
.support  from  the  wings  to  the  center  panel  seetion  of 
the  upper  wing.  This  results  in  tension  in  the  upper 
lonyi  runs  and  compression  in  the  lower. 

The  fuselage  struts  are  usually  made  of  spruce,  al- 
though ash  is  sometimes  used.  The  struts  are  joined  to 
the  longerons  by  means  of  metal  elips.  The  eonstruetion 
of  the  clips,  which  arc  usually  Lent  in  I"  shape,  is  such 
that  each  forms  a  partial  socket  for  receiving  the  end  of 
a  strut  or  struts.  In  general,  struts  are  subjected  to 
compression  only.  For  this  reason  spruce  is  the  favorite 
wood  for  struts  as  it  is  very  strong  along  the  grain  in 
tension  or  compression.  The  strength  of  steel,  weight 
for  weight,  would  have  to  be  18O.OOO  Ibs.  per  square  inch 
to  eijual  spruce  for  this  purpose.  Spruce  is  not.  however, 
very  strong  across  the  grain  and  splits  readily,  henee  it 
is  not  a  great  favorite  for  parts  subject  to  shearing  or 
cross-bending  stresses.  On  account  of  the  liability  of 
spruce  to  splitting,  the  ends  of  the  struts  are  sometimes 
encased  iii  copper  ferrules  or  bands.  This  prevents  crush- 
ing, splitting  and  chafing. 

Compression  Struts 

When  a  member  is  subjected  to  a  compression  force  it 
tends  to  bend  or  buckle  in  the  center.  To  resist  this  tend- 
ency, struts  subject  to  compression  stress  arc  made  larger 
in  the  center  than  at  the  ends. 

Ash  i>  selected  for  the  longerons  because  it  is  strong 
for  its  weight  (about  38  Ibs.  per  cu.  ft.),  very  elastic  and 
can  be  obtained  in  long,  straight-grained  pieces  free  from 
defects.  It  is  strong  across  the  grain  so  that  it  is  able 
to  resist  the  compression  due  to  clips  and  struts  attached 
at  \arious  points  on  the  longerons. 

The   metal   dips    in   which    the  ends  of  the  struts   are 


mounted   are   punched   from   sheet   steel,  then   pressed   to 
form.      They    are    frequently    made   of   two   or   three    sep 
aratc    pieces    which   are   then   electrically    spot-welded    to 
gether.     They   are  made  of  .*8   to   .:«!   per  cent,  carlton 
steel. 

The  lower  cross  mcml>crs  of  the  fuselage  at  stations  .( 
and  \.  numbered  from  the  front,  terminate  in  a  half  hinge 
to  which  the  lower  wing  sections  arc  attached  on  either 
side  of  the  fuselage.  These  cross-members  ser\e  as  com- 
pression members  when  a  machine  is  on  the  ground,  but 
when  it  is  in  the  air  they  become  tension  member*. 

Engine  Bearers 

The  engine  bearers  arc  made  of  spruce  with  a  strip  of 
ash  glued  on  top  and  bottom.  They  are  further  protected 
against  crushing,  at  points  where  the  engine  supporting 
arms  rest  on  the  sills  or  stringers,  by  means  of  a  copper 
hand. 

There  is  usually  a  fire  screen  between  the  engine  space 
and  the  cockpit.  This  is  to  prevent  injury  to  the  pilot 
so  far  as  possible  in  case  of  a  back  fire  or  fire  in  tin- 
engine  space. 

The  seat  rails  are  short  longitudinal  members  forming 
supports  for  the  pilot's  and  observer's  seats.     These  rails, 
which  arc  mounted  on  either  side  of  the  fuselage,  are  at 
taehed  to  adjacent   vertical  struts  at  the  proper  distance 
aloic  the  lower  longerons. 

The  rudder  bar  is  a  cross  bar  pivoted  at  its  center  and 
mounted  a  short  distance  above  the  floor  of  the  fuselage. 
It  is  used  to  control  the  vertical  rudder  and  is  operated 
by  the  pilot's  feet.  Ordinarily  the  ends  of  the  rudder 
bar  project  through  the  sides  of  the  fuselage,  working  in 
suitable  slots  cut  for  them,  and  the  rudder  wires  are  at- 
tached to  the  ends  of  the  rudder  bar  outside  of  the  fuse- 
lage. In  machines  fitted  with  dual  controls  there  arc. 
of  course,  two  rudder  bars  and  these  are  fastened  together 
by  means  of  wires  connecting  their  outer  ends.  The  rear 
of  the  two  rudder  bars  is  then  connected  to  the  vertical 
rudder  in  the  usual  way. 

Wing  section  struts  are  vertical  or  diagonal  struts 
mounted  above  the  fuselage  and  attached  by  means  of 
strut  sockets  to  the  upper  longerons.  The  wing  section 


298 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


struts  are  used  to  support  the  center  wing  panel  when 
the  machine  is  on  the  ground  and  when  in  the  air  they 
help  to  support  the  fuselage  from  the  center  panel,  the 
latter  being  supported  partly  by  the  upper  wing  sections 
which  are  attached  on  either  side  of  it  and  partly  by  the 
lower  wing  sections  which  are  braced  to  the  upper  sections 
and  also  attached  on  either  side  of  the  fuselage  as  pre- 
viously described. 

The  strut  sockets  in  which  the  lower  ends  of  the  wing 
section  struts  are  mounted  consist  of  U-shaped  steel  plates 
firmly  attached  to  the  upper  longeron.  The  wing  section 
struts  are  mounted  between  the  side  walls  of  the  socket, 
usually  by  means  of  a  heavy  through-bolt. 

Standard  Fuselage  Construction 

The  type  of  fuselage  just  described,  which  is  of  wood 
and  metal  construction,  may  be  said  to  represent  standard 
practice  in  this  country  at  the  present  time.  There  are, 
however,  other  types  of  construction,  such  as  the  all-steel 
fuselage.  In  this  the  shape  of  the  members  and  the  meth- 
ods of  joining  them  follow  closely  standard  methods  in 
structural  steel  work.  It  is  claimed  for  the  all-steel  con- 
struction that  it  is  lighter  for  a  given  size  machine  than 
the  wood  and  metal  or  composite  construction. 

The  fuselage  is  usually  covered  either  with  canvas  or 
linen  material  similar  to  that  used  for  wing  coverings  or 
else  with  very  thin  panels  of  veneered  wood.  In  the 
former  case  the  longerons,  struts  and  braces  must  carry 
all  the  weight  and  take  up  all  the  stresses  to  which  the 
fuselage  is  subjected,  but  when  a  veneered  wood  covering 
is  used,  it  contributes  materially  to  the  strength  of  the 
fuselage,  consequently  the  framework  of  the  latter  may 
be  made  lighter. 

There  are  also  fuselages  of  the  monocoque  type  in 
which  the  strength  is  obtained  not  by  a  truss  construction, 
but  by  the  form  and  nature  of  the  outer  shell  itself,  this 
being  made  up  of  alternate  layers  of  thin  wood  veneering 
and  cloth  until  the  desired  thickness  and  strength  are  ob- 
tained. The  various  layers  of  wood  veneering  are  laid 
with  the  grain  running  in  different  directions  in  the  differ- 
ent layers.  This  type  of  shell  or  body,  which  is  usually 
somewhat  fish-shaped,  possesses  the  necessary  strength 
and  elasticity  without  the  system  of  struts  and  tie  wires 
common  to  the  ordinary  or  trussed  type  of  fuselage.  The 
monocoque  construction  possesses  one  marked  disadvan- 
tage, however,  and  that  is  that  it  is  very  hard  to  repair 
in  case  of  slight  damage. 

It  may  be  added  that  the  monocoque  or  laminated  wood 
construction  is  far  more  common  in  foreign  countries,  par- 
ticularly France  and  Germany,  than  in  the  United  States. 

Landing  Gear 

The  landing  gear  is  an  assembly  of  struts,  fittings,  axle, 
wheels,  shock  absorbers  and  bracing  wires  whose  function 
is  to  enable  the  machine  to  rise  from  and  land  on  the 
ground  and  to  furnish  the  main  support  of  the  machine 
when  resting  on  the  ground. 

The  struts  of  the  landing  gear  are  of  streamline  shape 
to  reduce  the  resistance  when  flying.  They  are  usually 
made  of  well-seasoned,  straight-grained  ash  or  spruce. 
Very  often  they  are  further  strengthened  by  several  wrap- 
pings of  linen  twine.  The  struts  with  their  fittings  con- 


stitute important  members  and  should  be  carefully  exam- 
ined at  frequent  intervals.  Failure  or  collapse  of  these 
struts  would  be  almost  certain  to  cause  a  serious  accident 
when  landing. 

These  struts  are  attached  to  the  lower  side  of  the  fuse- 
lage, usually  to  the  lower  longerons  themselves  by  means 
of  metal  socket  fittings.  The  lower  ends  of  the  struts 
on  each  side  of  the  landing  gear  are  joined  together  by  a 
metal  bridge.  This  bridge  not  only  serves  to  tie  the 
lower  ends  of  the  struts  together,  but  it  also  forms  a  yoke 
or  housing  in  which  the  axle  box  plays  up  and  down. 
The  bridge  is  made  of  a  steel  stamping  or  drop  forging. 

The  axle  box  may  be  in  the  form  of  a  whole  box  or  a 
half  box.  When  it  is  in  the  form  of  a  half  box  it  is  gen- 
erally called  a  saddle.  Its  purpose  is  to  support  the 
axle  and  to  guide  its  vertical  motion  in  the  bridge.  The 
saddle  may  be  either  of  bronze  or  aluminum.  It  is  held 
in  its  place  in  the  bridge  by  a  wrapping  of  elastic  cord, 
which  consists  of  a  number  of  strands  or  bands  of  rubber 
bunched  together  and  enclosed  in  a  loosely-braided  cover- 
ing. 

The  assembly  of  the  saddle,  bridge  and  elastic  cords 
:s  called  the  shock  absorber. 

The  axle  is  made  of  steel  tubing  and  is  enclosed,  be- 
tween the  bridges  connecting  the  pairs  of  struts,  in  an 
axle  casing.  This  is  made  of  wood,  or  sheet  metal,  built 
around  the  axle  itself  and  is  of  streamline  shape  or  sec- 
tion to  reduce  air  resistance. 

The  wheels  are  the  ordinary  type  of  wire  wheels  of 
rather  small  diameter  and  usually  fitted  with  pneumatic 
tires.  They  do  not,  however,  ordinarily  run  on  ball  bear- 
ings, as  a  slight  amount  of  friction  in  the  wheel  bearings 
is  of  little  or  no  consequence  when  leaving  the  ground 
at  the  commencement  of  a  flight,  and  it  assists  somewhat 
in  bringing  the  machine  to  a  stop  without  going  too  far 
after  alighting.  The  sides  of  the  wheels  are  covered  with 
linen  cloth  discs  to  decrease  air  resistance. 

Not  all  landing  gears  are  like  the  one  described,  but 
this  may  be  taken  as  standard  practice.  Some  are  pro- 
vided with  a  skid  or  a  single  wheel  projecting  ahead  of 
and  above  the  main  wheels  for  the  purpose  of  preventing 
the  machine  from  taking  a  header  or  nosing  into  the 
ground  on  landing,  in  case  it  strikes  the  ground  at  too 
sharp  an  angle.  Other  minor  details  of  construction  will 
be  noted,  too,  on  different  types  of  machines,  particularly 
in  the  construction  of  the  shock  absorbers. 

The  tail  skid  is  a  skid  or  arm  projecting  below  the  fuse- 
lage near  its  rear  end.  The  purpose  of  the  tail  skid  is 
twofold;  first,  to  support  the  rear  end  of  the  aeroplane 
when  on  the  ground  or  in  landing,  and  prevent  damage  to 
the  rudder  and  elevators  and  their  controls,  and  secondly, 
to  act  as  a  drag  or  brake  to  assist  in  bringing  the  machine 
to  a  stop  when  landing.  The  tail  skid  is  frequently  hinged 
or  pivoted  where  it  is  attached  to  the  lower  longerons  and 
its  upper  end,  extending  above  the  pivotal  point,  fitted 
with  rubber  cords  similar  to  those  used  in  the  shock  ab- 
sorbers on  the  axle  of  the  landing  gear.  This  construc- 
tion acts  the  same  way  as  the  shock  absorber  and  prevents 
damage  to  the  empannage  and  rear  portion  of  the  fuselage 
when  landing. 

Aeroplanes  are  often  fitted  with  wing  skids  which  con- 
sist of  small  auxiliarv  skids  under  the  outer  ends  of  each 


RIGGING 


MO 


/Vase 


DrtniU  of  wing  construction 


lower  wing.  These  skids  ordinarily  do  not  come  into 
;u-tion  -ind  an-  only  pro\  ided  to  prevent  damage  to  the 
outer  win^s  in  alighting  on  rough  ground  or  in  case  a 
sudden  side  gust  of  wind  should  tend  to  upset  the  machine 
when  alighting  or  rising. 

Landing  Gear  of  Seaplanes 

:  'lanes  and  flying  boats  are  of  course  fitted  with 
entirely  different  types  of  landing  gear  from  that  de- 
scribed. Seaplanes  are  fitted  with  pontoons  or  floats  suit- 
able for  arising  from  and  alighting  on  the  water.  I'sually 
there  are  one  or  two  main  pontoons  under  the  forward 
section  of  the  fuselage,  these  corresponding  roughly  to 
I  lie  main  landing  gear  of  the  aeroplane.  There  is  also 
a  smaller  pontoon  mounted  under  the  rear  end  of  the  fuse- 

•H|  one  under  the  outer  end  of  each  wing  to  prc\ent 
the  wings  dipping  or  the  whole  machine  upsetting  in  rough 
water.  The  flying  boat  is  so  constructed  that  the  whole 
fuselage  i>  in  the  shape  of  a  boat  and  the  whole  machine 
is  therefore  supported  on  the  fuselage  when  resting  on 

tier  and  when  alighting  and  rising  from  the  water. 
The  Hying  boat  is  also  usually  fitted  with  small  auxiliary 
pontoons  under  the  outer  edge  of  the  wings  to  keep  the 
machine  steady  in  rough  water. 

Standard  Wing  Construction 

The  main  members  running  the  full  length  of  the  wing 
are  called  the  spars.  They  are  usually  spoken  of  as  front 
and  rear  spars.  Sometimes  the  front  spar  is  called  the 
main  spar. 

The    cross    members    joining    the    spars    together    are 

called   rilis.     There  are  two  kinds  of  these,  compression 

ril's  and  the  web  ribs.     The  function  of  the  web  ribs  is 

men  h    in    support   the   linen   covering  of   the   wings   and 

ist   the  lifting  force  of  the  air,  due  to  the  forward 

motion  of  the  aeroplane.     There   is   not  much  end  pres- 

igainst   these   ril>s.   therefore,   the  central   portion   is 

cut  out  for  the  sake  of  lightening  them.     The  function  of 

•inprcssion  rihs  is  not  only  to  resist  the  lifting  force 


of  the  air,  but  also  to  take  the  thrust  due  to  the  star 

w  ires. 

The  ribs  are  not  continuous,  that  is,  they  do  not  pass 
through  the  spars.  The  ribs  are  made  in  three  sections, 
the  nose  section,  center  section  and  tail  section.  The  nose 
section  of  a  rih  is  the  section  which  projects  forward  of 
the  front  or  main  spar.  The  renter  section  is  the  section 
between  the  front  and  rear  spars.  The  tail  .section  of  the 
rih  is  that  which  projects  to  the  rear  of  the  rear  spar. 
Tin'  nose  sections  and  tail  sections  are  sometimes  called 
nose  rihs  and  tail  rihs  and  are  also  frequently  .s|mkcn  of 
as  nose  webs  and  tail  webs,  because  they  are  cut  out  to  • 
web  form.  These  rib  sections  are  not,  of  course,  called 
upon  to  stand  compression  stresses,  as  these  stresses  are 
all  centered  in  or  taken  through  the  front  and  rear  spa- 

A  thin  strip  of  wood  running  from  the  nose  weh  across 
the  spars  to  the  rear  end  of  the  tail  webs  (lengthwise  of 
the  aeroplane  itself)  and  serving  to  bind  all  the  wing 
parts  or  rihs  together,  is  called  the  cap  strip.  There  is  • 
top  cap  strip  and  a  bottom  cap  strip  on  each  set  of  rib*. 

Entering  and  Trailing  Edges 

The  front  edge  of  the  wing  section  which  is  the  part 
carrying  the  nose  webs  or  nose  ribs  is  called  the  entering 
edge  of  the  wing.  The  rear  edge  of  the  wing  is  known 
as  the  trailing  edge. 

The  nose  webs  are  tied  together  by  a  strip  of  spruce 
running  full  length  of  the  wing  or  crosswise  of  the  aero- 
plane itself.  This  strip  forms  the  leading  edge  of  the 
wing  and  is  called  the  nose  strip.  From  the  nose  strip 
to  the  front  or  main  spar,  on  the  upper  side  of  the  wing, 
there  is  a  covering  of  thin  laminated  wood  called  the  nose 
covering.  Its  purpose  is  to  reinforce  the  covering  fabric 
as  it  is  at  this  point  that  the  effect  of  wind  pressure  due 
to  velocity  is  most  severe. 

Secondary  nose  ribs  are  placed  between  each  pair  of 
full  rihs  to  give  additional  support  to  the  nose  covering. 

There  are  usually  two  rod-like  members  running  from 
end  to  end  of  the  wing  through  the  central  part  of  the 


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TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


ribs.  These  are  called  stringers  and  are  used  for  the 
purpose  of  giving  lateral  stiffness  to  the  ribs. 

The  trailing  edge  of  the  wing  is  made  of  thin  flattened 
steel  tubing  attached  to  the  tail  webs  by  metal  clips. 

The  spars  are  continuous  throughout  their  length.  Fur- 
thermore, they  have  reinforcements  of  wood  at  the  points 
where  the  interplane  struts  connecting  the  upper  and  lower 
wings  are  attached.  Steel  bearing  plates  are  bolted  to 
the  wing  spars  at  these  points.  The  bolts  attaching 
these  bearing  plates  to  the  wing  spars  do  not  pass  through 
the  spars  themselves,  but  through  the  reinforcements. 
This  is  to  avoid  weakening  the  spars. 

Nearly  all  wood  used  in  wing  construction  is  spruce, 
with  the  exception  of  the  nose  covering  which  is  made  of 
bircli  or  gum  wood,  the  web  ribs,  which  are  made  of  lam- 
inated wood,  and  small  quantities  of  pine  or  other  woods 
in  the  sidewalk  and  other  unimportant  places. 

The  sidewalk  is  a  boxed-in  or  wood-covered  portion 
of  the  inner  end  of  the  lower  wing.  It  furnishes  a  solid 
footing  for  the  pilot  or  observer  when  entering  or  leaving 
the  cockpit  and  for  mechanics  working  around  the  engine, 
guns,  instruments,  control  mechanism,  etc. 

Steel  hinge  pieces  are  bolted  to  the  inner  ends  of  the 
wing  spars  and  serve  as  a  means  of  connecting  the  lower 
wings  to  the  fuselage  and  the  upper  wings  to  the  center 
wing  panel. 

Interplane  struts  are  vertical  or  inclined  wooden  struts 
of  streamline  section  used  to  transfer  compression  stresses 
from  the  lower  wings  to  the  upper  wings  when  the  ma- 
chine is  in  flight.  These  struts  are  used  in  conjunction 
with  diagonal  stay  wires  which  serve  to  transfer  the  load 
towards  the  center  of  the  machine  when  in  flight. 

The  stay  wires  are  divided  into  two  general  groups, 
those  which  take  the  drift  load  or  fore-and-aft  stresses 
due  to  the  forward  motion  of  the  aeroplane,  and  those 
which  take  the  lift  load  or  vertical  load  due  to  the  weight 
of  the  machine  itself  and  the  vertical  resistance  when  in 
the  air.  The  lift  wires  are  again  divided  into  those 
which  take  the  load  when  the  machine  is  flying  and  those 
which  take  it  when  on  the  ground.  The  wires  which  take 
the  lift  load  when  the  machine  is  in  the  air  are  called  the 
flying  wires,  and  those  which  take  the  load  when  on  the 
ground  are  called  ground  or  landing  wires. 

Drift  and  Anti-Drift  Wires 

The  set  of  wires  in  the  wings  which  carry  the  drift 
load  when  flying  are  called  the  flying  drift  wires,  or  drift 
wires  for  short.  There  is  no  reversal  of  load  in  these 
wires  when  the  machine  is  on  the  ground,  but  opposition 
wires  are  necessary  to  maintain  structural  symmetry. 
These  latter  are  called  the  anti-drift  wires. 

When  the  wings  are  covered  it  is  of  course  impossible 
to  inspect  the  internal  stay  wires  of  the  wings,  hence 
every  precaution  must  be  taken  to  guard  against  corro- 
sion. The  wire  used  at  this  point  is  tin  coated  before 
assembling,  the  steel  parts  of  the  turnbuckles  and  other 
fittings  are  copper  plated  and  when  completely  assembled, 
all  the  metal  parts  are  given  a  coat  of  enamel  paint.  All 
screws,  tacks  and  brads  are  of  brass  or  copper. 

Wings  are  covered  with  a  closely  woven  fabric.  At 
present  unbleached  linen  seems  to  give  the  best  satisfac- 
tion. Owing  to  its  scarcity,  however,  a  satisfactorv  sub- 


stitute is  being  sought  for.  A  cloth  made  of  long  fibre 
sea  island  cotton  is  used  to  some  extent  and  makes  a 
fairly  satisfactory  substitute. 

Linen  fabric  weighs  31/-;  to  -1%  oz.  per  sq.  yd.  and  has 
a  strength  of  60  to  100  Ibs.  per  in.  of  width.  Its  strength 
is  increased  25  to  30  per  cent,  by  doping,  however.  The 
weight  of  cotton  fabric  is  2  to  1  oz.  per  sq.  yd.,  its  strength 
30  to  60  Ibs.  per  in.  of  width,  and  its  strength  is  increased 
20  to  25  per  cent,  by  the  application  of  dope. 

The  cloth  surfaces  or  wing  coverings  must  be  taut, 
otherwise  on  passing  through  the  air  they  would  vibrate 
or  whip.  This  would  not  only  increase  the  resistance  to  a 
great  extent,  but  soon  would  lead  to  the  destruction  of 
the  fabric.  A  preparation  called  dope  is  used  to  tighten 
up  the  fabric  and  give  a  smooth,  taut  surface.  It  also 
tends  to  make  the  cloth  weather-proof. 

Dope  should  be  easy  of  application,  durable,  fire  re- 
sisting and  have  a  preserving  effect  on  the  cloth.  Dopes 
at  present  are  divided  into  two  classes  or  chemical  groups, 
those  which  are  made  from  a  base  of  cellulose  nitrate  or 
pyroxylin  and  those  made  from  a  cellulose  acetate  base. 
The  base  is  dissolved  in  a  suitable  solvent,  such  as  acetone 
for  instance,  and  sometimes  other  substances  are  added  to 
preserve  flexibility  or  prevent  drying  out  and  cracking 
and  checking  or  to  modify  shrinkage. 

The  greatest  difference  between  these  two  dopes  is  in 
their  relative  inflammability.  The  acetate  dope  makes 
the  fabric  not  fireproof,  but  slow  burning.  A  cloth 
treated  with  this  dope  will  shrivel  and  char  before  burn- 
ing, but  one  treated  with  nitrate  dope  will  burst  into  flame 
immediately  on  the  application  of  a  lighted  match  or 
when  exposed  to  a  strong  spark  or  puncturrd  by  a  flaming 
bullet,  etc. 

Inspection  windows  are  often  inserted  in  wing  sections 
over  and  under  certain  control  joints  where  the  latter  are 
carried  inside  the  .wing  section  itself.  For  instance,  the 
aileron  control  cables  are  frequently  run  inside  the  lower 
wing  sections  to  a  pulley  attached  to  the  front  or  main 
spar  opposite  the  middle  of  the  aileron,  the  cable  then 
passing  down  at  a  slight  angle  and  through  a  thimble 
or  sleeve  in  the  lower  covering  of  the  wing  section  to  the 
point  where  the  cable  is  attached  to  the  aileron  control 
marst.  With  this  construction  inspection  windows  would 
be  set  in  the  upper  and  lower  coverings  of  the  lower  wing 
immediately  above  and  below  the  pulley  over  which  the 
control  cable  passes.  The  inspection  windows  are  usually 
of  celluloid  or  other  transparent  material  firmly  sewn 
into  the  wing  covering  material. 

Stay  Wires  and  Splices 

Stay  wires  and  cables  are  used  extensively  in  aeroplane 
construction.  Much  of  the  safety  of  the  machine  and 
pilot  depends  upon  the  quality  of  the  material  in  the  stay 
wires,  the  care  used  in  adjusting  them  and  on  the  char- 
acter of  the  terminal  splices. 

Three  kinds  of  materials  are  used  for  stay  wires :  solid 
or  aircraft  wire,  stranded  wire  or  aircraft  strand,  and  a 
number  of  strands  twisted  together  to  form  a  cable  and 
known  as  aircraft  cord.  Aircraft  wire  is  a  hard  drawn 
carbon  steel  wire  coated  with  tin  to  protect  it  against  cor- 
rosion. Its  strength  runs  from  200,000  to  300,000  Ibs. 
per  sq.  in.,  depending  upon  how  small  it  is  drawn.  Draw- 


RIGGING 


.•(in 


<=a     j 


«^fcc 


>tc|.s   in   making  an  en.l   splice   in   s,,|j(|   »irr 

ing  increase!  iolh  the  strength  and  hardness  of  this  type 
of  wire,  but  if  drawn  until  too  hard  it  cannot  be  bc,,t  with 
safety.  The  aim  is  to  pr.iducc  .-,  wire  ,,f  maxim,,,,, 
stren-tl,.  ,,,  „,(!,  sufficient  toughness  to  allow  it  to  h.nd 
without  fracture.  A  standard  test  for  Unding  is  to 
grip  the  wir,  ,,,  .,  \  ice  whose  jaws  ha\e  been  round,  d  off 
16  in.  radius.  ,nd  bend  the  wire  back  and  forth 
fcroagfa  an  angle  of  ivd,  -  Had,  bend  of  «MI  d,-g.  counts 
as  one  Lend.  The  minimum  number  of  bends  fl)r  various 
si/,  s  of  aircraft  wires  should  be  as  follows: 

»ir.    of   II.  ;v   s    (Mllire    \-0.     6_    5  ,„.„,,„  with,iu,    fra,.,|lr,. 

PM  wir.    ...    II.  A;   S.  gaugr   No.     8-    »  brmls  without  fracture. 

B   *  B  Wo.  lo       ||   |H.n,|s  without  fracture. 

r   wire  of    II.   \    S     u.,,,^.    \,,     i.,         ,;    |M.|1(U    ttj,,H,u,    frn(.tlln. 

wire  of  l\.  &  S.  gaugr  No.   It       _•:,  Len.K  without   fractiirr 

For  wire  ,,f  ».  &  S.  gauge  No.   Hi       :i»  |M-i,,|s  without   fnictiire. 

Air,  raft  strand  is  composed  of  n  number  of  small  wires, 
usually  Hi.  twisted  together.  The  individual  wir- 
tlie  strand  are  galvanized  or  zinc  coated  before  being 
twisted  into  the  strand.  The  complete  strand  is  more 
flexible  than  a  solid  wire  of  the  same  diameter  and  is 
therefore  mor,  suitable  for  stay  wires  that  are  subject 
to  \  ibration. 

The  stay  wins  of  the  fuselage  at  the  engine  and  wing 
panels  .re  of  aircraft  strand  or  cord,  but  for  the  remain- 
ing stay  wiros  of  the  fuselage  aircraft  wire  is  ordinarily 

Is,   .| 

Aircraft   cord    is  much   more   flexible   than   Hie   strand. 

•  d   tor  control  cables   where  these  must    pass  over 

aratively    small    pulleys.      The   usual   constrm-tion   of 

iff  cord  is  7  strands  of  ]<l  wires  each  twisted  together 

to   form   a   cable.      This   specification    is   known   as    ~  \  19 

i  ord.     The  individual  wires  of  the  cord  are  very 

imall  and  are  tin-plated  before  being  stranded. 

For   .,   given   diameter,   the   solid   wire   is   stronger   than 
•ithcr  th,    strand  or  cord.     Weight   for  weight,  however, 
he  cord   is  a   little  stronger  than  the  wire,  as  shown   by 
lowing  table. 


Wright 

p*r  100  ft 

8At  ll.s. 

6.47  Ibs. 


St  n-ngth  for  a 

pivcu  iliiiiui-ter 
5,300  Ilis. 
VOO  Ibs. 


Strength  fora 
given  Wright 


A  wire  or  cord  is  no  stronger  than  its  terminal  splice. 

I  he   splice   in  iy   be    formed   in   a   variety   of    ways.      For 

"lid    wir.     the    formation    of    the    eye    is    important.      An 

ye   in    which   the    reverse  curve   has   the   same    radius  as 

proper  is  called  a  perfect  eye  and  is  the  one  recom- 


mend, d        Th.    ms.d.    ,|M1u,.,r  „.    ih,    ,,,    should   l.e  alH.,,1 
tunes  the  di  under  of  tl.,-  win    ,|s,  || 

aed   capped    wir 

rrule.  somewhat   lik.    ,  .o,l,,l   s|irill)f  ,)„„,,„, ,   ,„  ,  m 

'".   ,s   sl.p,,,.,!   ,,,,r   ,,„.    w,n    and    .1,,    fri,    ,,„, 

I'll,  r    is   then    U-nt    hack    OTer   th,    ferrule       Such   „ 

'•n.iMml   will   |ln(,    .,„  ,,,i..j(.r,  r   |1M(     (>f 

tl'e  stn.^th  of  th.    nir,-   ..self.      \\  |,,  n   this   t,,,,-  ,,f   ,,.rill 
f«'ls  •!  is  usually  l,y  sl.pping.      If  the  fre,-  end  ,,l  tl,. 
•  ""I  -l-wn.  ,,f,,r  |M.illK  ,H.n,   ,,,I(.k   (|V|.r  ,|l(.    fi.rnilr 
•Hi  an  additional  wrapping  of  wire.  Ih,    elli.-.encv   of  the 
ernun.d    as   „    whole    will    I,,     m.r.as,,)    to    HO    per 'cent     of 
t  >••   strength  of  the   wire.      If  ,|lr   w|1()|,.   ,,.rmillll|    js   SI1, 
end    the    efldency     Mill     U-    mere. •,,,,)     I,,     IM.I     p,T    ,.,.,,, 

rill"K    I"    >t«tic    tests.      This    is    misleading,    how 

i"  such  tests  take  no  account  of  live  load  sir, or  nl.ra 

tlnll 

Another  form  of  terminal  is-  made  by  substituting  a  thin 
metal  ferrule  or  section  of  flattened  tulx-  for  the  wrapped 
"in  ferrule.  It  can  be  made  secure  either  by  soldering 
twisting  after  U-ing  put  in  place.  This  terminal  for 
I've  or  vibrational  loads  is  ,u|>crior  to  the  wrapped  win- 
terminal  as  then  is  not  so  much  difference  jn  mass  l» 
the  wire  and  the  ferrule. 

Aircraft  Strand  Terminals 

The  terminal  eye  of  the  aircraft  strand  is  formed  around 
a  thimble.  The  free  end  of  the  strand  is  brought  around 
the  thimble  and  either  wr;ip|«d  to  the  main  strand  with 
small  wires  and  soldi-red,  or  the  free  end  is  spliced  into 
the  main  strand.  Hefore  bending  around  the  thimble, 
the  strand  is  wrapped  with  fine  wire  in  order  to  prevent 
flattening  or  caging  of  the  •rfrand. 

The  terminal  eye  of  the  aircraft  cord  is  always  made  bv 
splicing   the    free   end    of   the   cord    into   the   main    strands 
after   wrapping   the   cord    around   a    thimble.     Sometimes 
the   splice   is   soldi-red    but   more   often   it    is    wrapped   with 
harness  twine.      Foreign  engineers  are  opposed  to  solder 
ing.  claiming  that    the   disadi. -ullages   in    the   wav   of  cor 
rosion  and  overheating  of  the   wire  outweigh   the  advan- 
tages of  the  stronger  terminals. 

The  theory  of  the  splice  is  simple.  A  strand  or  wire  of 
the  free  end  is  wrapped  around  a  strand  or  wire  of  the 
main  cord,  care  being  taken  to  have  the  iay  of  the  wires 
the  same.  Three  to  five  complete  turns  are  given,  three 
for  the  first  and  four  to  five  for  the  last  weaves  of  the 
splice  in  order  to  taper  the  splice  gradually. 

Objections  to  tnliirrinfl. —  The  most  serious  objections 
to  soldering  are:  a.  overheating;  b.  corrosive  action  of 
fluxes  It  is  very  easy  to  overheat  and  soften  the  wire 
and  this  is  all  the  more  serious  because  the  softening  tak 
place  at  a  point  where  the  wire  is  enlarged  by  the  joint. 
The  str.ss  is  naturally  localised  at  this  point. 

Some  of  the  so-called  non-corrosiir  fluxes  will  upon 
application  In-  found  to  IM-  more  or  less  corrosi\c.  F.\.n 
with  strictly  non  corroxi\  e  fluxes,  tiiere  is  a  carbonaceous 
residue,  due  to  heat.  dri\,n  into  the  interstices  between 
tin-  wires  of  strands  or  cordV  This  serves  as  a  holder 
for  moisture  and  will  in  time  cause  corrosion. 

The  corrosive  effects  of  acid  fluxes  can  be  neutralized 
by  the  application  of  an  alkaline  solution,  such  as  soda 
water.  Washing  the  soldered  splice  of  a  solid  wire  witli 


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TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


such  a  solution  is  very  effective,  but  with  strands  and 
cords,  where  the  acid  is  driven  into  the  interior  through 
the  application  of  heat,  it  is  questionable  whether  any 
system  of  washing  will  eliminate  or  neutralize  the  acid. 
Corrosion  of  the  interior  wires  of  a  strand  or  cord  may 
be  concealed  by  a  perfectly  good  exterior,  giving  an  en- 
tirely false  appearance  of  security. 

Turnbuckles 

Turnbuckles  are  made  of  three  parts,  the  ferrule  or 
sleeve,  and  the  two  ends.  To  distinguish  the  ends,  they 
are  called  the  yoke  and  eye  ends,  or  the  male  and  fe- 
male. 

Great  care  should  be  exercised  when  tightening  or  loos- 
ening turnbuckles  that  the  cables  are  not  untwisted  or 
frayed.  If  the  cables  are  untwisted  a  caging  of  the 
strands  results  which  greatly  weakens  the  cable.  Cable 
that  has  been  caged  should  be  replaced.  No  pliers  should 
be  used  when  tightening  or  loosening  turnbuckles.  The 
correct  method  is  to  use  two  drift  pins  or  nails,  one 
through  the  terminal  eye  of  the  cable  to  prevent  the  end 
of  the  cable  twisting,  the  other  through  the  hole  in  the 
barrel  of  the  turnbuckle.  Pliers  will  scar  the  wires,  which 
is  objectionable  for  three  reasons,  the  first  two  of  which 
mav  lead  to  serious  consequences.  These  reasons  are: 
First,  breaking  the  protective  coating  given  to  guard 
against  corrosion.  Second,  a  nick  or  scar  in  a  wire  or 
cable  which  would  weaken  it  considerably.  The  wire  or 
cable  may  not  show  much  reduction  of  strength  under  a 
static  load  or  test,  but  with  a  live  or  vibrational  load  the 
strength  is  greatly  reduced  and  a  slight  nick  will  deter- 


mine the  point  of  fracture.  Third,  disfiguration  of  the 
parts  is  offensive  to  the  eye  and  bespeaks  slouchy  or  care- 
less workmanship. 

Locking  Devices 

A  fair  proportion  of  accidents  occurs  to  moving  mech- 
anism through  nuts  or  other  threaded  fastenings  working 
loose.  It  is  safe  to  say  that  several  hundred  patents 
have  been  taken  out  for  nut-locking  devices,  but  of  this 
great  number,  a  few  only  are  of  practical  value  and  used 
to  any  extent.  The  castellated  nut  and  cotter  pin  used 
of  course  with  a  drilled  bolt  or  stud  is  one  of  the  few 
devices  that  finds  large  application.  It  is  generally  used 
in  automobile  and  aeroplane  work.  The  spring  locking 
washer  is  another  good  device.  This  is  used  where  the 
fastening  is  of  a  permanent  or  semi-permanent  character. 
Another  method  is  to  batter  or  hammer  down  the  end  of 
a  bolt  a  little.  This  should  be  practiced  only  as  a  last 
resort  or  as  an  absolutely  permanent  job  and  must  be 
carefully  done,  otherwise  serious  damage  will  result  to 
the  bolt  and  nut.  It  is  sufficient  to  close  one  thread  on  the 
bolt  for  part  of  the  circumference  only. 

Turnbuckles   are   secured   against  turning  or  loosening 
by  running  a  wire  through  the  adjusting  hole  in  the  turn- 
buckle  sleeve  and  carrying  the  wire  back  and  binding  i 
around  the  ends  of  the  turnbuckle. 


The  proper  way  to  lock  a  turnbuckle 


C  H.M'TKK   XII 
ALIGNMENT 


Hv  tin  ti-nn  aeroplane  alignment  is  meant  the  art  of 
truing  "|>  an  aeroplane,  and  ailj  listing  tin-  parts  in  tli.-jr 
proper  relation  to  each  other  as  designated  in  the  ...  r,. 
plane's  spccilicatioiis.  Tin-  inln-rrnt  stability,  tin-  sp,  ,  ,1. 
th<-  rate  of  climb,  tin-  ctfieiency.  in  short  the  airworthin.  -ss 
of  an  aircraft  depend  in  large  measure  on  its  correct  align- 
nifiit.  1  ,,r  this  reason  the  importance  of  careful  and 
rorro-t  alignment  cannot  be  overestimated. 

'I'ln  instructions  as  gixcn  in  this  chapter  are  not  in- 
tend..! to  be  a  complete  and  exhaustive  treatise  on  the 
who],  subject  of  aeroplane  alignment,  but  are  designed 
rather  to  give  the  beginner  a  good  general  idea  of  how 
the  work  is  done.  Thus  with  these  instructions  as  • 
ground  work  he  can  become  proficient  in  the  work  after 
baring  hail  good  practical  experience  in  the  hangars. 

The  work  of  aligning  an  aeroplane  divides  naturally 
into  several  distinct  and  separate  groups  or  divisions  —  a. 
fuselage,  b.  horizontal  and  vertical  stabilisers,  c.  landing 

d.  center  w  ing  section,  e.  wings,  f.  controls. 
.Iliiinmenl  of  futrlage. —  The  fuselage  is  aligned  be- 
fore leaving  the  aeroplane  factory  and  normally  this  align- 
ment will  last  for  some  time.  The  fuselage  alignment 
should  be  checked  over  carefully,  however,  after  an  aero- 
plane has  been  shipped  in  disassembled  condition.  Strains 
on  the  fuselage  caused  by  rough  handling,  bad  landings, 
etc..  will  make  it  necessary  to  re-align  it. 

H'  tore  attempting  to  align  any  part  of  an  aeroplane 
the  erection  drawings  should  be  referred  to  if  available, 
and  the  directions  furnished  by  the  makers  should  be 
followed  carefully  unless  the  operator  has  had  a  great 
deal  of  previous  experience  upon  the  particular  type  of 
aeroplane  to  be  aligned,  and  is  familiar  with  better  meth- 
ods of  procedure  than  those  recommended  by  the  maker. 
In  general  the  procedure  in  aligning  a  fuselage  will  be 
about  as  follows:  A  horizontal  reference  plane  is  usually 
specified  by  the  makers  in  connection  with  the  fuselage. 
Sometimes  the  top  longerons  are  taken  as  this  reference 
plane,  in  which  case  they  are  to  be  aligned  horizontally, 
laterally,  and  longitudinally  from  a  specified  station  to  the 
tail  post.  Sometimes  horizontal  lines  are  drawn  on  the 
vertical  fuselage  struts,  and  the  fuselage  is  so  aligned 
that  these  lines  all  fall  in  the  same  horizontal  plane. 

Alignment  of  Longeron* 

In  the  first  case,  after  the  fuselage  has  been  placed  in 
a  flying  position,  the  top  longerons  are  aligned  for  straight- 
using  n   straight   edge   and   a   spirit   level   to  aid   in 
finally    placing    them    laterally    and    longitudinally    in    a 
horizontal  plane. 

303 


The  longerons  are  next  aligned  symmetrically  with  re- 
spect tc,  the  imaginary  vertical  plane  of  symmetry  through 
the  fore-and-aft  axis  of  the  fuselage.  There'  are  two 
general  methods  of  doing  this,  as  follows : 

I  irst  Method  —  The  center  points  are  marked  on  all 
horizontal  fuselage  struts.  A  small,  stout  cord  is  stretched 
from  the  center  of  the  fuselage  none  to  the  tail  post  and 
the  horizontal  bracing  wires  adjusted  until  the  centers 
of  the  horizontal  struts  fall  beneath  this  line.  A  small 
surveyor's  plumb  bob  is  held  at  different  |minU  so  that 
the  suspending  cord  just  touches  the  fore-and-aft  align- 
ing cord.  The  centers  of  the  bottom  horizontal  struts 
should  fall  directly  below  the  bob. 

Second  Method  —  A  plumb  line  is  dropped  from  the 
center  of  the  propeller  and  from  the  tail  |x>st  and  a  string 
is  stretched  on  the  ground  or  floor  between  these  two 
points.  Plumb  bobs  drop|ied  from  the  centers  of  the 
horizontal  struts  must  point  to  this  line. 

The  whole  fuselage  alignment  is  checked  to  make  sure 
that  it  agrees  with  the  specifications.  If  the  aeroplane 
has  a  non-lifting  tail,  it  would  be  advisable  as  the  next 
step  to  support  the  fuselage  in  such  a  way  that  the  rear 
part  (about  two-thirds  of  the  total  fuselage  length)  re- 
mains unsupported,  and  then  re-check  the  fuselage  align- 
ment once  more. 

All  turnhuekles  should  then  be  securely  locked  and  the 
fuselage  carefully  inspected. 

Horizontal  and  Vertical  Stabilizers 

The  vertical  stabilizer  is  examined  to  see  that  the  bolts 
holding  it  in  place  are  properly  drilled  and  cotter-pinned, 
also  to  see  that  it  is  set  parallel  or  dead  on  to  the  direc- 
tion of  motion.  It  is  trued  up  vertically  by  the  turn- 
buckles  on  the  tie  wires  or  brace  wires  connected  to  it. 
These  turnbuckles  arc  then  properly  safetied. 

The  horizontal  stabilizer  usually  is  braced  with  tie 
wires  fitted  with  turnbuckles.  By  means  of  these  its  trail- 
ing edge  should  be  made  straight  and  at  right  angles  to 
the  horizontal  center  line  of  the  fuselage.  All  bolts 
fastening  the  horizontal  stabilizer  to  the  fuselage  should 
be  inspected  to  make  sure  they  are  properly  drilled  and 
cotter-pinned.  All  turnbuckles  should  be  safetied,  as  pre- 
viously shown. 

.Ilifinmrnt  of  landing  gear  or  undrr-carriagr. —  In  as- 
sembling an  aeroplane  which  has  been  completely  dis- 
mantled, the  landing  gear  should  be  assembled  to  thr 
fuselage  and  aligned  with  it  before  the  wings  are  at- 
tached. In  assembling  and  aligning  the  landing  gear, 
the  fuselage  should  be  so  supported  that  the  landing  gear 


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hangs  free  and  the  wheels  do  not  touch  the  ground. 
The  fuselage  is  placed  in  the  flying  position,  or  at  least 
in  such  a  position  that  the  lateral  axis  is  horizontal. 
There  are  three  general  methods  of  aligning  the  landing 
gear,  as  follows: 

First  Method  — A  small  plumb  is  dropped  from  a  poi 
on  the  fore-and-aft  center  line  of  the  fuselage  above  the 
axle  of  the  landing  gear.  A  tack  is  placed  in  the  exact 
center  of  the  axle  casing  or  a  scratch  is  made  on  the  axle 
at  its  center.  The  transverse  tie  wires  are  then  adjusted 
until  the  tack  or  center  line  mark  falls  exactly  below  the 
plumb  bob.  The  wires  are  made  moderately  tight.  The 
exact  degree  of  tautness  required  cannot  very  well  be 
described;  it  is  a  matter  of  experience  or  personal  instruc- 
tion. All  turnbuckles  are  safetied  and  the  landing  gear 
inspected  carefully.  The  strut  fittings  and  the  elastic 
shock  absorbers  should  be  inspected  very  carefully. 

Second  Method  —  The  two  forward  transverse  tie  wires 
are  adjusted  until  equal  in  length,  then  the  rear  trans- 
verse tie  wires  are  similarly  adjusted  until  they  also  are 
equal  in  length.  All  transverse  tie  wires  are  tightened 
equally  and  the  turnbuckles  safetied.  The  landing  gear 
is  then  given  a  final  inspection. 

Third  Method — The  transverse  tie  wires  are  adjusted 
until  the  axle  is  horizontal  as  shown  by  a  spirit  level. 
This  adjustment  is  made  with  the  fuselage  in  the  flying 
position  or  with  the  lateral  axis  horizontal.  The  trans- 
verse tie  wires  are  tightened  equally  to  the  correct  taut- 
ness,  the  turnbuckles  safetied,  and  the  landing  gear  in- 
spected as  before. 

Center  Wing  Section 

Alignment  of  center  wing  section. —  The  fuselage  is 
first  placed  in  the  flying  position,  and  the  center  wing 
section  adjusted  symmetrically  about  the  fore-and-aft 
center  line  of  the  fuselage  in  plan.  A  tack  driven  in 
the  middle  of  the  leading  edge  of  the  center  panel  will 
then  be  directly  above  the  center  line  of  the  fuselage. 
This  is  tested  with  a  small  plumb  bob  and  checked  by 
measuring  each  pair  of  transverse  tie  wires  to  see  if  the 
•  two  wires  of  each  pair  are  equal  in  length. 

The  alignment  for  stagger  is  made  by  adjusting  the 
stagger  or  drift  wires  in  the  fore-and-aft  direction  until 
the  leading  edge  of  the  center  panel  projects  the  required 
distance  ahead  of  the  leading  edge  of  the  lower  plane  as 
given  in  the  aeroplane  specifications.  This  alignment  is 
checked  by  dropping  a  plumb  bob  from  the  leading  edge 
of  the  center  panel  and  measuring  forward  in  a  hori- 
zontal plane  from  the  leading  edge  of  the  lower  plane  to 
the  plumb  line.  The  adjustment  for  stagger  fixes  the 
rigger's  angle  of  incidence.  All  turnbuckles  are  safetied 
and  the  alignment  re-checked. 

Alignment  of  wing*. —  Before  any  attempt  is  made  to 
align  the  wings  the  fuselage  should  be  carefully  inspected 
to  make  sure  that  it  is  properly  riggeed  and  in  proper 
alignment.  Failure  to  do  this  may  cause  much  delay  and 
waste  of  time  in  aligning  the  wings. 

The  next  step  is  to  make  a  general  inspection  of  the 
wings,  noting  if  all  bolts  and  clevis  pins  are  properly 
cotter-pinned.  Note  particularly  the  clevis  pins  where 
the  interplane  brace  wires  are  fastened  to  the  upper 
plane  fittings.  One  of  the  largest  aeroplane  makers  in 


tliis  country  puts  these  clevis  pins  in  head  down.  In  this 
position  if  the  pins  are  not  properly  cottered,  there  is 
great  danger  of  their  working  loose  and  dropping  out, 
disconnecting  the  wires.  Such  matters  are  more  easily 
remedied  before  the  wings  are  aligned  than  afterwards. 

Loosen  all  wires  between  the  planes  including  flying 
wires,  ground  wires,  stagger  wires  and  external  drift 
wires.  Examine  the  turnbuckles  to  see  that  the  same 
number  of  threads  show  at  both  ends.  If  not,  take  the 
turn-buckle  apart  and  remedy  this.  It  will  mean  a  sav- 
ing of  time  in  the  end  if  these  matters  are  looked  after 
before  the  actual  truing  up  of  the  wings  is  begun. 

Flying  Position 

Place  the  fuselage  in  the  flying  position  as  denned  in 
the  aeroplane's  erection  drawings.  This  may  mean  align- 
ing the  top  longerons  or  the  engine  bed  or  other  specified 
parts  laterally  and  longitudinally  horizontal.  This  must 
be  done  carefully,  using  a  good  spirit  level,  because  the 
wings  are  aligned  from  the  fuselage  upon  the  assumption 
that  this  flying  position  is  correct.  If  it  is  necessary  to 
get  into  the  cockpit  or  in  any  other  way  disturb  the 
fuselage  during  the  alignment  of  the  wings,  make  sure 
that  the  fuselage  is  still  in  the  correct  flying  position  be- 
fore proceeding  further. 

Lateral  dihedral  angle.—  There  are  three  common  meth- 
ods of  adjusting  for  lateral  dihedral: 

Aligning  Board 

First  Method  —  Aligning  Board.1  If  an  aligning  board 
is  available  its  use  saves  considerable  time  due  to  the  fact 
that  the  rigger  secures  the  lateral  dihedral  angle,  straight- 
ness  of  wing  spars,  and  correct  angle  of  incidence  near 
the  wing  tips  all  at  the  same  time.  The  protractor  level 
should  read  directly  in  degrees.  Set  this  instrument  at 
the  number  of  degrees  dihedral  stated  in  the  aeroplane's 
specifications.  Place  the  aligning  board  parallel  to  the 
front  spar  (by  measuring  back  from  the  strut  fittings) 
and,  keeping  the  flying  and  stagger  wires  loose,  pull  up 
on  the  ground  wires  until  the  bubble  on  the  protractor 
level  reads  almost  level.  Since  the  aligning  board  is  a 
straight  edge  it  is  easy  to  keep  the  front  spar  perfectly 
straight  by  glancing-  beneath  the  aligning  board  occasion- 
ally. It  should  rest  on  at  least  three  ribs,  one  near  each 
end  and  one  near  the  middle.  The  space  between  the 
other  ribs  and  the  aligning  board  should  be  slight. 


^Dihedral  Board 

FIG.  34  —  Method  of  using  short  dihedral  board 

Place  the  aligning  board  in  front  of  and  parallel  to  the 
rear  spar.  Adjust  the  ground  wires  until  the  rear  spai 
is  straight  and  the  dihedral  is  slightly  greater  than  called 
for  in  the  maker's  specifications.  Check  at  the  front  spar. 
It  will  now  be  the  same  as  the  rear.  If  not  make  it  so. 

i  See  note  on  aligning  boards  at  end  of  this  chapter. 


ALK.XMKN  I 


• 

In.     r,        Points  of  iiieiisiin-ment   for  wing  alignment 

Now  tighten  ilow  n  on  all  flying  wires  except  those  to 
the  overhang,  if  then-  is  overhang.  Test  each  pair  of  Hy- 
ing wires  for  equal  taiitn,  ss  by  striking  with  the  edge  of 
the  hand  and  watching  their  vibration.  The  loose  win- 
has  Ih,  greatest  amplitude  of  vibration.  The  lateral  di- 
hedral should  now  be  exactly  as  called  for  in  the  spcciti 
cations. 

After  aligning  both  wings  for  dihedral  as  stated  above, 
both  wings  will  lie  the  same  height  if  the  fuselage  is  h\el 
laterally.  Check  the  height  of  the  wings  by  making  the 
distance  BA  (see  Fig.  35)  equal  to  DC  measured  from 
the  longerons  opposite  the  butt  ends  of  the  front  spars 
on  the  lower  wing  panels.  V  is  a  tack  in  the  middle  of 
the  leading  edge  of  the  center  section  panel.  With  a 
steel  tape  measure  the  distance  V'A  and  VC.  These  dis- 
tant is  should  be  equal. 

Kijiially  good  results  may  be  obtained  by  using  a  pro- 
tractor spirit  level  in  conjunction  with  an  accurate  straight 
edge. 

Second  Method  —  If  a  good  aligning  board  is  not  avail- 
able the  string  method  may  be  used.  Fig.  36  shows  the 
arrangement  of  the  string  which  should  be  .small,  smooth 
and  tightly  drawn. 

K-.-p  the  stagger  wires,  flying  wires  and  nose  drift 
wires  loose  as  in  the  first  method.  Increase  the  dihedral 
angle,  by  tightening  the  ground  wires,  keeping  the  panels 
straight  by  sighting.  The  greater  the  dihedral  angle  the 
'••r  the  distance  Y  (see  Fig.  36).  The  table  below 
shows  the  variation  for  customary  range  of  lateral  di- 
hedral: 

TABLE  FOR   I.  \TIKAI.  DIHF.nRAI.  ANGLES 
X 


Deg 

Inches    Mist  a  nee    from 
|Miint   of  support   of 
string  to  eiel  of  spar 

Inches   Distance   from 
•ml  of  spar  vertically  up 
to  th«-  liori/ont  il  strinir 

0 

100 

0 

1 

100 

!% 

2 
3 

4 

100 
100 
100 

3% 
5% 

7 

5 

100 

8lVi« 

6 

100 

Ktyta 

7 

100 

U%« 

8 

100 

'•"%« 

9 

100 

1J% 

10 

100 

17*, 

Fio.  30— Alternative   nirUMKi  of  aligning  for  dihedral 

'I'lir  distance  X  will  probably  not  be  exactly   loo  in.  M 
given  in  tin-  table,  hut  sin,-,-  X  and  \  i,u.r,  ..,„. "jn  ,|,,.  „„„,,. 
proportion    tlii.s    i-,    vrry    simple.      For    example,    tin-    ili> 
tance  X    (convenient   to  m,  asure)   on  a   hipl.ine   |,a\  i,,g  a 

ieg.  lateral  dihedral  angle  may  be,  say  {••  ft.  i>  in.,  or 
l.'iO  in.,  which  is  one  and  one-half  times  10(1  in. 

The  table  gives  Y  e«|unl  to  S'/i  in.  for  .S  dcg.  Our  X 
i*  one  and  one-half  times  the  X  in  the  table.  Then  our 
V  must  be  one  and  one-half  times  :,  i  ,  in  (  the  Y  given  in 
the  table),  which  equals  ~~ ^  „>..  which  is  the  proper  dis- 
tance up  to  the  string  when  the  wing  has  tin-  cornet  lat- 
eral dihedral. 

In  determining  the  distance  Y,  always  measure  the 
vertical  distance  up  to  the  string  from  near  the  inner  edge 
of  the  wing  panel,  not  from  the  center  section  panel.  The 
correct  lateral  dihedral  angle  having  been  obtained,  pro- 
ceed further  as  in  the  first  method. 

Third  Method — On  aeroplanes  having  sweep-buck  the 
string  method  is  rather  difficult  to  apply.  If  an  aligning 
board  such  as  used  in  the  first  method  is  not  available, 
then  a  .short  dihedral  hoard  may  In-  made  which  will  scric. 
Fig.  37  shows  the  construction  and  Fig.  31  the  method  of 

I  ' 


Fin.  :17  —  Short  ililieilr.il  Uwrd 


using  such  a  board.  It  is  plain  that  a  separate  board 
must  be  made  for  each  aeroplane  having  a  different  di- 
hedral from  the  others  at  a  flying  field.  Another  disad- 
vantage of  this  board  is  the  fact  that  it  must  IN-  used  IN- 
tween  struts  on  the  spars  and  is  so  short  that  it  is  apt 
to  be  affected  greatly  by  unei|iial  rib  heights  and  any 
lack  of  straight  nets  in  the  spars. 

After  obtaining  the  correct  dihedral   proceed  as  in  tin- 
first  method. 

Stiii/i/i-r  is  usually  given  in  aeroplane  specifications  as 
a   linear  measurement  in   inches.     The  specifications    will 


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of 


C  orH  (w/iictnver  method  of  measuring 
ffi*   specifications  Co//  forlis  the  sfoyoer. 

FIG.  38  —  Methods  of  measuring  stagger 

tell  whether  it  is  to  be  measured  on  a  projection  of  the 
chord  or  as  a  horizontal  distance.  (See  Fig.  38.)  It  is 
important  to  measure  the  stagger  in  the  manner  directed. 

The  stagger  of  the  wings  is  fixed  at  the  fuselage  by  the 
stagger  of  the  center  wing  section.  Align  for  stagger  by 
adjusting  the  stagger  wires  between  interplane  struts. 
Slight  adjustments  only  should  be  necessary.  Fig.  38 
shows  the  method. 

In  exceptional  cases  the  flying  and  ground  wires,  front 
and  rear,  nearest  the  fuselage,  are  used  in  adjusting  the 
stagger,  which  is  usually  found  to  be  correct,  however, 
after  slight  adjustments  of  the  stagger  wires. 

Stagger  is  sometimes  given  as  an  angle  of  stagger  in 
degrees.  This  can  be  converted  into  inches  by  the  use 
of  the  lateral  dihedral  table  on  page  305.  In  this  case  AB 
in  Fig.  38  corresponds  to  X  in  the  table,  and  Y  in  Fig. 
38  will  be  proportional  to  Y  in  the  table.  For  instance 
if  AB  in  Fig.  38  is  50  in.  in  a  given  aeroplane,  or  one- 
half  of  X  in  the  table,  and  the  stagger  is  given  in  the 
aeroplane's  specifications  as  7  deg.,  then  the  amount  of 
stagger  Y  (Fig.  38)  would  be  one-half  of  the  12  3/16  in. 
given  in  Column  Y  in  the  table  opposite  7  deg. 

Overhang. —  If  the  aeroplane  has  much  overhang  it  is 
usually  supported  by  mast  wires  above  and  flying  wires 
below.  See  that  the  flying  wires  are  loose.  Tightening 
one  set  of  wires  against  an  opposing  set  throws  undue 
stress  in  members.  Tighten  up  on  the  mast  wires  until 
the  overhang  inclines  very  slightly  upward.  Now  tighten 
up  on  the  flying  wires  below  until  the  spars  are  straight. 

The  leading  and  trailing  edges  of  all  wing  panels  should 
now  be  straight.  In  case  there  should  be  small  local  bows 


Spirit  Level 


Sfraight   Ee/ye 

Fio.  39  —  Measuring  angle  of  incidence  with  straight-edge  and 
spirit  level 


Straight  £Jye 

FIG.  43  —  Another  method  of  measuring  angle  of  incidence. 
It  can  also  be  done  advantageously  by  using  a  straight  edge  in 
conjunction  with  a  protractor  spirit  level 

in  the  spars,  with  a  little  careful  adjusting  of  wires  these 
can  usually  be  distributed  equally  between  the  upper  and 
lower  wing  panels  so  that  their  effect  will  be  lessened. 
Fixing  the  lateral  dihedral  or  the  angle  of  incidence  for 
either  upper  or  lower  plane  automatically  adjusts  it  for 
the  other  plane. 

Rigger's  angle  of  incidence. —  Check  the  lateral  dihedral 
to  make  sure  that  it  has  not  been  altered  in  making  other 
adjustments.  If  it  is  correct,  front  and  rear,  and  the 
spars  are  straight,  then  the  angle  of  incidence  should  be 
correct  all  along  the  wing.  Figs.  39  and  40  show  two 
methods  of  testing  this.  If  the  set  measurements  A  or  B 
are  known,  the  first  method  (Fig.  39)  can  be  used.  If 
the  angle  AOB  is  given  in  the  specifications  then  the  sec- 
ond method  (Fig.  40)  can  be  employed.  Test  the  angle 
of  incidence  near  the  fuselage  and  beneath  the  interplane 
struts. 

Wash-out  and  wash-in. —  Due  to  the  reaction  from  the 
torque  of  the  propeller  the  aeroplane  tends  to  rotate  about 
its  longitudinal  axis.  To  counteract  this  the  wing  which 
tends  to  go  down  (sometimes  referred  to  as  the  "  heavy  " 
wing)  is  drawn  down  slightly  at  its  trailing  edge  towards 
its  outer  end,  or  in  other  words  it  is  given  a  slight  addi- 
tional droop  at  this  point.  This  is  usually  referred  to  as 
a  "  wash-in."  The  wing  on  the  other  side  of  the  machine 
is  given  a  slight  upward  twist,  or  "  wash-out  at  a  cor- 
responding point.  In  single-engined,  right-hand  tractors 
wash-in  is  given  to  the  left  wing  and  wash-out  to  the  right. 
To  increase  the  angle  of  incidence  the  rear  spar  must  be 
warped  down  by  slackening  all  the  wires  connected  to  the 
bottom  of  the  strut  and  tightening  all  which  are  connected 
to  the  top  of  the  struts,  until  the  desired  amount  of  wash-in 
is  secured.  This  process  is  reversed  to  secure  wash-out. 

For  purposes  of  increased  stability  wash-out  is  some- 
times given  both  wings  although  of  course  some  lift  is  lost 
by  doing  this.  If  it  is  still  desired  to  compensate  for  the 
reaction  due  to  the  propeller  torque,  more  wash-out  is 
given  on  one  side  than  on  the  other.  The  side  having  the 
least  wash-out  then  has  wash-in  relative  to  the  other  side. 

Over-all  measurements. —  Tighten  the  external  drift 
wires  only  moderately  tight.  The  following  over-all 
measurements  should  now  be  taken,  using  a  steel  tape  (see 
Fig.  35):  Make  BA=DC  and  LH  =  MN.  Then  OA 
should  equal  OC  and  HE  should  equal  EN.  These  meas- 
urements should  be  made  at  points  on  the  upper  wing 
panels  as  well  as  the  lower,  making  eight  check  measure- 
ments in  all. 

All  turnbuckles  are  now  safetied  (Fig.  41).  Make  a 
general  final  inspection  of  the  wings  to  make  sure  that 


ALKi.N.MI.N  T 


.•{07 


Block. 


*•+ 


-'       linliiiiln.il  method  ,if  connc,  tin^r  aileron  controls 

hat  hern  overlimkrtl.  It  mutt  lie  rrmrmbrrrd  that 
in  m,ikni<i  on,-  n-ljintmrnt  other  adjuttment*  made  pre- 
.«/-/  man  '"'  thrown  tlit/litly  off,  to  that  u-hen  the  u-inyi 
are  finnlli,  aliened  it  it  a  good  plan  to  check  the  lateral 
dihedral,  .itn;/;/,-r,  angle  of  incidence,  etc.,  to  make  ture 
I  tin  t  nil  are  correct. 

Contrail  —  Aileront. —  Fasten  the  hand  wheel,  stick,  or 
.shoulder  yoke  controlling  the  ailerons  in  its  central  posi- 
tion. If  the  ailerons  have  brace  wires  on  each  side  (se« 
anil  these  wires  are  supplied  with  turnbuckles, 
.straighten  up  the  trailing  edge  by  adjusting  these  wires. 
If  the  ailerons  are  connected  as  in  Fig.  !•:!  the  trailing 
edj:.-s  must  l>,  straightened  as  the  ailerons  are  aligned  on 
the  aeroplane. 

Then-  is  difference  of  opinion  about  drooping  the  trail- 
ing edge  of  ailerons  In-low  the  trailing  edge  of  the  plane 
to  which  they  are  fastened.  At  some  fields  the  turn- 
buckles  on  the  aileron  control  cables  arc  so  adjusted  that 
the  trailing  edge  of  the  aileron  lines  up  with  the  trail- 
ing edge  of  the  wing  panel  to  which  it  is  hinged.  At 
other  fields,  from  '  s  in.  to  :! ,  in.  of  droop  is  given  the 
trailing  edge  of  the  aileron.  Ix-cause  it  forms  a  part  of  a 
lifting  surface  and  it  is  reasoned  that. slack  will  IK-  taken 
out  of  the  lower  control  cables  when  the  machine  gets 
into  the  air.  I'nless  directed  otherwise  it  perhaps  is  ad- 
visable  to  give  little  or  no  droop. 

The  ailerons  should  work  freely  and  respond  quickly 
with  no  feeling  of  drag  when  the  hand  wheel  is  turned 


•ToeA 

I 


/Vvfrvabr 


Sfrt/ffht  Ed,. 
Teat  for  Srrotffttnttt 
r  — Tr>-ing  an  aligning  board  for  itraightnriw 


•>r  the  stick  moved  even  very   slightly.       Improper  coiling 
of  rabies  when  a  machine  is  dismantled  will  ruin  tins 
ilitic.n  .itMiut  as  quickly  as  anything  ,-,,ii|(|.     c.ir<-  must  !„• 
liken   not   to   put  too  muc-li   tension  on   the   cables.     The 
pulleys  around  which  they  run  on-  light,  and  not  alw 
so  strong  as  they  might  be.     Cracked  pulleys  may  so: 
times  Ix-  found  on  old  macliin.  s. 

Intcrplanc  ailerons  are  adjusted  so  that  both  arc  in  the 
same  plane  when  rontrol  js  neutral.  Tin-  angle  at  whieh 
they  are  set  must  be  given  by  the  makers  or  d.  t.  rinin. -d 
by  experiment  and  experience. 

Ktevatort.—  Fasten  the  bridge  or  stick  control  in  its 
central  position.  Adjust  the  turnburkles  on  the  control 
cables  until  the  elevators  are  in  tin  ir  ncutr.-il  position  and 
both  are  in  tin-  snme  plane.  Tighten  the  control  cables 
enough  to  remove  lost  motion. 

liudden. —  Fasten  the  rudder  footbar  in  its  mid-posi- 
tion and  adjust  the  turnbuckles  until  the  rudder  is  in  the 
neutral  position,  and  the  cables  are  tight  enough  to  re- 
move lost  motion. 

Both  elevators  :md  rudders  usually  carry  brace  wires 
with  turnbuckles  which  can  be  used  in  straightening  their 
trailing  edges. 

Notes  on  Aligning  Boards 

To  be  useful  an  aligning  I  o.ird  first  of  all  must  be  true. 
Fig.  11  shows  a  method  of  testing  such  a  board  for 
straightness.  (See  A  and  B,  Fig.  44.)  Also  by  sup- 
porting the  board  as  shown  and  setting  the  protractor  lei  i  I 
at  different  degrees  the  protractor  can  be  tried  out.  Ref- 
erence to  the  table  for  lateral  dihedral  on  page  :<<>;>  shows 
the  difference  in  thickness  of  the  blocks  for  the  different 
angles.  The  zero  point  may  be  tested  by  setting  the  in- 
strument at  y.cro  and  supporting  the  aligning  hoard  on 
some  surface  known  to  !>r  level. 

Tin  inclin.ition  for  the  board  used- in  the  third  method 
of  aligning  for  lateral  dihedral  can  be  determined  from  the 
lateral  dihedral  table.  Fifty  inches  make  a  convenient 
length  for  such  a  board,  in  which  ease  the  Y  (see  Fig.  45) 
is  just  half  of  that  given  in  the  table  for  lateral  dihedral 


I  : 


Slum-ing  series  method  of  connecting  ailerons  in  pair* 


Test  of   Proh+c/br  U~/ 


Fio.  43  —  Alipninfr   board   us.-,!   with  Uble   for   lateral  dihedral 

angles 


CHAPTER  XIII 


CARE  AND  INSPECTION 

Cleanliness  —  Control  cables  and  wires  —  Locking  devices  —  Struts  and  sockets  —  Special  inspection  —  Lubrication  — 
Adjustments  —  Vetting  or  sighting  by  eye  —  Mishandling  on  the  ground  —  Airplane  shed  or  hangar  —  Estimating 
time  —  Weekly  inspection  card  form. 


Cleanliness. —  One  of  the  most  important  items  is  clean- 
liness of  all  parts  of  the  plane.  After  every  flight  the 
machine  should  be  thoroughly  cleaned.  To  remove  grease 
and  oil  from  the  wings  and  covered  surfaces,  use  either 
gasoline,  acetone  or  castile  soap  and  water.  If  castile 
soap  cannot  be  obtained,  be  sure  the  soap  used  contains 
no  alkali  or  it  will  injure  the  dope.  In  using  the  gaso- 
line or  acetone,  do  not  use  too  much  or  it  will  also  take 
off  the  dope.  A  good  way  to  use  the  latter  is  to  soak 
a  piece  of  waste  or  rag  and  rub  over  the  grease  or  oil, 
theB  wipe  off  with  a  piece  of  dry  waste.  When  using 
soap  and  water  be  careful  not  to  get  any  inside  the  wing 
as  it  is  liable  to  warp  the  ribs  or  rust  the  wires. 

When  mud  is  to  be  removed  from  the  surfaces  it  should 
never  be  taken  off  while  dry,  but  should  be  moistened  with 
water  and  then  removed. 

Other  parts  of  the  machine  should  be  kept  thoroughly 
clean  to  keep  down  the  friction. 

Control  cables  and  wires. —  All  cables  and  wires  should 
be  inspected  by  the  rigger  to  see  that  they  are  at  the  cor- 
rect tension.  Also  see  that  there  are  no  kinks  or  broken 
strands  in  any  of  the  cables  or  strands.  Do  not  forget 
the  aileron  balance  cable  on  top  of  the  wings.  When  a 
wire  is  found  to  be  slack  do  not  tighten  it  at  once  but 
examine  the  opposing  wire  to  see  if  it  is  too  tight.  If  so 
the  machine  is  probably  not  resting  naturally.  If  the 
opposing  wire  is  not  over-tight  then  tighten  the  slack  wire. 

All  cables  and  strands  and  external  wires  should  be 
cleaned  and  re-oiled  about  every  two  weeks.  The  oil 
should  be  very  thin  so  that  it  will  penetrate  between  the 
strands. 

Locking  devices. —  All  threaded  fastenings  and  pins 
should  be  inspected  very  frequently  to  see  that  there  is 
no  danger  of  anything  coming  loose. 

Struts  and  sockets. —  Since  the  struts  are  compression 
members,  largely,  they  should  be  examined  on  the  ends 
for  crushing  and  in  the  middle  for  bending  and  cracking. 

Special  inspection. —  A  detailed  inspection  of  all  parts 
of  the  machine  should  be  made  once  every  week.  Usually 
there  is  an  inspection  sheet  provided  for  this  purpose. 
If  no  sheet  is  obtainable,  then  one  should  be  made  before 
the  inspection  is  started.  Make  a  list  of  all  the  parts  to 
be  inspected,  starting  at  a  certain  point  on  the  machine, 
and  following  around  until  that  point  is  reached  again. 
When  each  part  or  detail  is  inspected  it  should  be  checked 
on  the  sheet  as  defective  or  O.  K. 

A  good  weekly  inspection  card  form  is  given  on  the 
following  page. 

Lubrication. —  Always  see  that  all  moving  parts  are 
working  freely  before  a  flight  is  made.  This  includes 
undercarriage  wheels,  pulleys,  control  levers,  hinges,  etc. 

308 


Adjustments. —  The  angle  of  incidence,  dihedral  angle, 
stagger  and  position  of  the  controlling  surfaces  should  be 
checked  as  often  as  possible  so  that  everything  will  be 
all  right  at  all  times.  Alignment  of  the  undercarriage 
should  be  made  so  that  it  will  not  be  twisted  and  thus  cut 
down  the  speed  of  the  machine. 

I'etting  or  sighting  by  eye. —  This  should  be  practiced 
at  all  times.  When  the  machine  is  properly  lined  up, 
look  at  it  and  get  a  picture  in  your  mind  of  just  how  it 
looks.  Then  when  anything  becomes  out  of  line  it  can 
be  easily  detected  without  using  any  tools.  See  that  the 
struts  are  in  the  same  plane  when  looking  at  the  front 
or  side  of  the  machine.  The  dihedral  angle  also  can  be 
checked  by  this  method  of  sighting.  Some  flyers  become 
so  expert  that  they  can  check  the  alignment  of  the  whole 
machine  by  eye. 

Distortion 

Always  be  on  the  lookout  for  dislocation  of  any  of  the 
parts.  If  any  distortions  cannot  be  corrected  by  adjust- 
ment of  the  wires,  then  the  part  should  be  replaced. 

Mishandling  on  the  ground. —  Great  care  should  always 
be  taken  not  to  overstress  any  part  of  the  machine.  Mem- 
bers are  usually  designed  for  a  certain  kind  of  stress  and 
if  any  other  kind  is  put  upon  them,  some  damage  is  likely 
to  occur.  When  pulling  an  aeroplane  along  the  ground, 
the  rope  should  be  fastened  to  the  top  of  the  undercar- 
riage struts.  If  this  cannot  be  done,  then  fasten  the  rope 
to  the  interplane  struts  as  low  down  as  possible. 

Never  lay  covered  parts  down  on  the  floor  but  stand 
them  on  their  entering  edges  with  some  padding  under- 
neath. Struts  should  be  stood  on  end  where  they  cannot 
fall  down. 

Hangar. —  The  hangar  at  all  times  should  be  kept  in 
the  best  possible  condition.  Never  have  oily  waste  or 
rags  lying  around  on  the  floor  or  benches,  as  these  are 
liable  to  catch  fire.  No  smoking  should  be  allowed  in  or 
near  the  building.  Do  not  have  oily  sawdust  spread 
around  on  the  floor  to  catch  the  oil  but  have  pans  for  this 
purpose. 

In  making  replacements  of  defective  parts,  have  a  place 
for  the  old  pieces.  Never  allow  them  to  be  put  where 
they  will  be  mistaken  for  new  parts. 

Each  tool  should  be  kept  in  a  certain  designated  place 
and  when  anybody  borrows  a  tool,  be  sure  that  he  puts 
it  back  where  it  belongs. 

Estimating  time. —  When  any  repairs  are  to  be  made, 
learn  to  estimate  the  time  required  for  the  job.  With  a 
little  practice  this  can  be  done  very  accurately.  It  may 
help  sometime  in  making  a  report  to  an  officer  in  charge 
as  to  when  an  aeroplane  will  be  ready  to  go  out  again. 


AM)  INSI'KCTIOX                                                    :,„., 

Weekly  Aeroplane  Inspection  Card  --irult: 

I,,,/,            /;,,  It-.    ''otters 

./.>,./„»,    .V,, !/..*.                                    „  StraightneM 

h:n,,in,   \,, M,,k, I/,,,/,  |  »'K«t 

I  .ft 

I  his    e«M    urn--!    !«•    in. ill,-    mil    li\     I  iel.l    Inspector    for  /;/<•  r»».»  • 

I-MTJ    machine    iiiuliT    his    charge,    sign.-,!    |,v    him.    ami    must    I,,  ,l.,Mn^ 
tiin.nl  oxer  t,,  II,,.  Chirf   Inspector  as  soon  •$  i,,.,,l,    out. 

1 1  inc.   .-,ssci,il.|\    (lubricate  with  graphite  grease) 

l.niK/in,/   ijrar:  ..  j|y       . 

Wire   Iriisi.in    Wear   

Wire  terminals      Hinge  pins  :,u<l  .-..It.  -rs 

Strut  sockets   (nuts,  liolts)    Control  win-  connection   (must) 

Loose  spokes                                                    K rayed  control  wire  (wheel) 

\\lesgreascd                                                   (pulleys  and  guides)   . 

irity  .if  wheels  to  a\lc   Control   wirrs   frnyc«l   nt   any   part  of  thrlr  Irnfrth 

Shix-k    .iliMirU-r    riihlx'r    iniivt  Ix-  rrplac«l  «t  iin.-r. 

'1'irr  iiitl.iti.in  l'iill.-ys    

/'r../..  II.  r  Crraxrd 

(•..n.liti.m  ,,f  I,],,,!,.. Vrrr  runninfr  . 

Hnl.  .•i-.-riiil.ly   (I.,,!!-,  w.i.hrr..  .-..ttrrs)    \i\fiM   « Herons   upjicr    ...  knrrr.. 

urity  to  shaft  '-<•"  "Herons  upjier  lower 

Tliru.st    Fiurlayr   rrar  interior: 

fut,t.,,l,    nnit:  Wirr   Inisions    

•r,-iisi,,ii  fusrliip.  bracing  '  ••'"(-•••rong    

Tension  and  t. -riiiinals  winjt  drag  hracinjf ttings  

Knpine  !«•<!  and  Ix.lts   \li){niiient     

,,,,,,„:  Stahilizrr: 

I  ,  ,  „  ,   ,  Bolts  nuts,  cotters,  braces   

It.nliati.r    full    rrrliral  ft>: 

/;„,,,„,.  Holts,  nuts,  cotters,  braces  

Valves  —  K  mldrr : 

Intake  clearance Hinfre  assembly    

I  \lmiist  olrarnnre   Security     

Spark  plufrs  —  Wear   

Clean    Hlnjfe  pins  and  cotters 

( iiip    Control  win-  connections   

-l.uretor—  Ma»t    

S<-curity  to  manifold  l-'oothar 

Bracing Kmyed  control  wire  

Manifold  joints N'ote:     Control  wires  frayed  at  any  point  of  their  length 

Oil  t<i>ttm:  IMllst  |K>  repl««-«l  »»  once. 

•  kage     Pulleys 

( )il   (grade)    

Oil  reservoir  full  Frpe  r«">nlng 

Elrralort: 

Hinge  assembly    

6  ' 


Distributor  lx>anl Wear 


Breaker  point  clearance HtafB  pta»  «rf  «0*toW  ...... 

I  rans,,,,ss,on  (drive)  wear Contr((|  wjn.  ,.„„„„.„„„,       ,„„,,   

tlr  control:  Control  wire  connections  —  post   

1'iillcys    Frayed  nintrol  wire   

Wiring    Note:     Control  wires  frayed  at  any  point  of  their  length 

Bell  cranks  and  connections  must  be  replaced  at  once. 

i»r  tytttm :  Pulleys   

Tank    Creased  

Gasoline  leads  and  connections   Free  running  

1'iinip Right  elevator 

Gasoline  in  tank    full  Left  elevator 

j,>inli:                                                                                                  Tail  tkiil: 
'  I-ower  wing  —  right    Skid    

Ix>wer  wing       left Fittings   

I'pprr  wing  —  right    Shock  absorber 

I'pper  wing       left  Control*: 

icirrt:    (tension,    terminals    clevis    pins,    cotters,    safety  Free    and     proper    operation     (lubricate    with    graphite 

wires)  (frease)    

Flying  wires  —  right  wing Elevator   

I  h  ing  wires  —  left  wing  K  udder    

Landing  wires  —  right  wing Aileron    

Landing  wires  —  left  wing ./ li<;nmrn/  nf  rittirr  markinr : 

Wires,  fittings,  turnbuckles,  cleaned  and  greased 

firtin,!*:  (bolts,  nuts,  cotters) 

Right  wing,  upper  lower 

I-eft  wing,  upper  lower (Signed)                        Field  Inspector. 


CHAPTER  XIV 


MINOR  REPAIRS 

Patching  holes  in  wings  — Doping  patches  —  Terminal  loops  in  solid  wire  —  Terminal  splices  in  strand  or  cable  —  Sol- 
dering and  related  processes  —  Soft  soldering  —  Hard  soldering  — Brazing  — Sweating  procedure  in  soldering  — 
Fluxes  —  Melting  points  of  solders. 


The  materials  used  in  patching  holes  in  linen-covered 
surfaces  is  unbleached  Irish  linen,  the  same  kind  as  used 
in  covering  the  wings.  The  material  must  be  unbleached 
or  it  will  not  shrink  the  required  amount.  Generally  the 
kind  of  dope  used  is  Emaillite  dope,  although  the  acetate 
or  nitrate  dopes  could  be  used.  The  dope  should  be  ap- 
plied in  a  very  dry  atmosphere  or  on  a  sunshiny  day  at 
a  temperature  not  less  than  65  deg.  F.  A  brush  or  a 
piece  of  waste  may  be  used  to  apply  the  dope. 

In  patching  a  hole  the  first  thing  to  be  done  is  to  clean 
the  surface  of  the  old  dope.  To  do  this,  fine  sand  paper 
may  be  used  or  acetone,  gasoline  or  dope.  In  using  the 
sand  paper,  care  should  be  taken  not  to  injure  the  cover- 
ing. When  using  the  acetone  or  gasoline,  it  should  be 
put  on  the  surface,  allowed  to  stand  for  a  while  to  soak 
up  the  old  dope,  then  scraped  off.  The  same  method  is 
applied  when  using  dope  to  clean  the  surface. 

After  the  surface  is  cleaned,  the  edges  of  the  hole 
should  be  sewed  if  it  is  of  any  considerable  size.  To  do 
this  sewing  linen  thread  and  a  curved  needle  are  used. 
The  stitches  should  not  be  closer  together  than  !/£>  in.  and 
far  enougli  back  from  the  edge  so  that  there  is  no  dan- 
ger of  their  tearing  out.  With  a  small  hole,  such  as  a 
bullet  hole  for  instance,  it  is  not  necessary  to  do  any 
sewing.  When  the  hole  is  several  inches  square,  a  piece 
of  unbleached  linen  should  be  sewed  in  to  give  a  body  for 
the  top  patch  so  that  it  will  not  be  hollow  in  the  center 
after  it  is  dry.  The  sewing  up  of  holes  should  be  done 
after  the  surface  is  cleaned  so  that  any  slackness  may  be 
taken  up  before  the  patch  is  applied. 

After  sewing  is  finished  the  patch  is  cut.  It  should  be 
made  about  1  to  2  in.  larger  on  each  side  than  the  hole. 
The  edges  of  the  patch  must  be  frayed  for  about  1/4  in., 
this  being  done  to  prevent  them  from  tearing  easily. 

Dope  should  now  be  applied  to  the  wing.  Generally 
several  coats  are  put  on  so  that  there  will  be  a  sufficient 
amount  to  make  the  patch  stick  well.  After  the  last  coat 
is  applied  the  patch  should  be  put  in  place  immediately 
before  the  dope  has  a  chance  to  dry.  Any  air  bubbles  and 
wrinkles  should  now  be  worked  from  under  the  patch  by 
rubbing  with  the  fingers,  and  more  dope  put  on  top  of 
the  patch.  Usually  there  are  six  or  seven  coats  of  dope 
applied  on  top  of  the  patch,  allowing  time  for  each  coat 
to  dry  before  another  is  applied. 

Any  small  amount  of  slackness  in  the  patcli  will  prob- 
ably be  taken  out  as  the  linen  shrinks.  If  the  patch  is 
hollow  after  the  dope  is  thoroughly  dry,  however,  it  is  not 
a  good  patcli  and  should  be  removed.  A  good  patch 


310 


should  be  tight  around  the  edges  as  well  as  in  the  center 
over  the  hole  and  should  contain  no  creases  or  air  bubbles. 

Terminal  Splices 

A  loop  or  splice  must  be  formed  in  the  end  of  every 
brace  wire  or  control  cable  where  it  is  attached  to  a  strut 
socket,  turnbuckle,  control  mast,  or  other  form  of  term- 
inal attachment.  The  manner  of  making  the  loop  or 
splice  in  the  wire  will  vary  according  to  the  type  of  wire 
or  cable  used.  The  terminal  in  the  end  of  a  solid  wire 
is  made  in  the  manner  shown  in  Fig.  33. 

There  are  several  points  to  be  observed  in  making  tin's 
type  of  terminal  splice,  as  follows:  (a)  The  size  of  the 
loop  should  be  as  small  as  possible  within  reason,  as  a 
large  loop  tends  to  elongate,  thus  spoiling  the  adjustment 
of  the  wires.  On  the  other  hand,  the  loop  should  not  be 
so  small  as  to  cause  danger  of  the  wire  breaking,  due  to 
too  sharp  a  bend,  (b)  The  inner  diameter  of  the  loop 
should  be  about  three  times  the  diameter  of  the  wire,  and 
the  reverse  curve  at  the  shoulders  of  the  loop  should  be 
of  the  same  radius  as  the  loop  itself.  The  shape  of  the 
loop  should  be  symmetrical.  If  the  shoulders  are  made 
to  the  proper  radius  there  will  be  no  danger  of  the  fer- 
rule slipping  up  towards  the  loop,  (c)  When  the  loop 
is  finished  it  should  not  be  damaged  anywhere.  If  made 
with  pliers  there  will  be  a  likelihood  of  scratching  or 
scoring  the  wire,  which  would  weaken  it  greatly.  Any 
break  or  score  in  the  surface  coating  of  a  wire  destroys 
the  protective  covering  at  that  particular  point  and  the 
wire  will  soon  be  weakened  by  exposure.  A  deep  nick 
or  score  would  greatly  weaken  the  wire  and  eventually 
result  in  breakage  at  that  point. 

Splicing  a  strand  or  cable. —  The  splice  in  the  end  of  a 
strand  or  cable  is  entirely  different  from  the  terminal 
of  a  solid  wire.  The  end  of  the  strand  is  led  around 
a  thimble  and  the  free  end  spliced  into  the  body  of  the 
strand  or  cable  just  below  the  point  of  the  thimble.  Such 
a  splice  is  afterward  served  with  twine,  but  the  serving 
should  not  be  done  until  the  splice  has  been  inspected 
by  whoever  is  in  charge  of  the  workshop.  The  serving 
might  cover  bad  workmanship  in  the  splice. 

Soldering. —  Terminal  loops  or  splices  in  solid  wire  and 
also  splices  in  the  ends  of  strand  or  cord  are  sometimes 
soldered  after  being  formed.  There  are  some  objections 
to  soldering  at  these  points,  however,  as  outlined  on  page 
301.  The  ensuing  instructions  for  soldering  work  will 
prove  valuable  in  case  where  this  method  of  securing  a 
terminal  splice  is  considered  desirable. 


I: 


MINOR    R  I.I'.  MRS 


.-ill 


Jinninif  uf  m ft  alt  hi/  3<iltirrin</  anil  rrlatnl 
There  are  several  inrtli<Mls  of  joining  metals  tojji -tlu-r  by 
alloy-,  which  nit-It  at  n  lower  ti  inpcr.itiirc  than  tin-  metals 
to  IK-  joined.  These  processes  differ  in  tin-  allov  s  u-.  .1 
anil  in  tlit-ir  melting  temperatures.  Tin  \  in  ili\  iilrtl  intn 
four  classes,  11  follows  : 

Soft       Mlllll    rillU'.  Tills      111.    til. M!       is      till"      I'lll         Used       111 

till  smithiiii;  generally,  where  tin-  solder  is  null,  il  hv 
iiu-.-iiis  ol  .-i  hut  soldering  coppi  r  n\rr  thr  surfaces  to  be 
joinril.  'I'lii  solilrr  nsi  d  in  this  process  has  a  low  melting 
point. 

Mini   soldering.—  This   method    is   usually   used   m 

jcwclrv    w.irk  :IIH|   in  tin-  ,-irts.  when-  :i  higher  t.  mperatiire 

must  In    withstood.      Tin-  joining  metal  in  this  case  has  a 

iniirli  higher  MM  ItniLT  IMIIIII   th  tn  soft   soldi  r.  and  must  be 

I   with  .1  blow   torch  to  mnkc  it  flow. 

Hra/ini;.  This  process  differs  from  hard  solder- 
inir  onlv.  in  the  t'.-irt  that  the  joining  metal  has  a  still 
higher  melting  point.  It  is  used  principally  in  motor- 
cycli  .  bievclc  anil  automobile  construction,  where  greater 
strength  is  required. 

»>w  .  at  inc.  Tins  is  a  process  used  where  tin-  \- 
to  lie  joined  can  tirst  lie  fitted  together,  then  individually 
•  d  with  solder,  then  clamped  together  and  heated  until 
the  solder  Hows  md  cements  them  solidly  together.  This 
method  allows  for  a  more  perfect  joint  being  made.  The 
more  accurately  the  parts  are  fitted  together  the  stronger 
the  union  will  lie.  Also,  the  thinner  the  coat  of  solder- 
ing material,  within  reasonable  limits,  the  stronger  the 
joint. 

All  of  the  above  methods  are  used  more  or  less  in  aero- 
plane construction  and  maintenance,  but  the  one  that  is 
most  generally  used  is  the  first,  or  soft-soldering  method. 
Cle-niliness  is  of  prime  importance  in  making  joints  or 
fastening  by  any  of  these  methods.  In  soldering,  the 
first  step  is  to  see  that  the  soldering  copper  is  clean  and 
well  tinned,  for  this  may  determine  the  success  or  fail- 
ure of  the  job.  There  are  several  ways  of  cleaning  and 
tinning  the  soldering  copper,  but  the  one  recommended 
b  to  heat  the  copjxr  to  about  600  deg.  F.,  then  dip  the 
point  (jiiiekly  into  a  cup  or  jar  containing  ammonium 
chloride  (Nil,  (1)  and  granular  tin  or  small  pieces  of 
r.  If  any  considerable  amount  of  work  is  to  be  done, 
an  earthen  jar  or  a  teacup  can  be  used,  and  kept  partly 
tilh  d  with  this  mixture. 

Tinning  Soldering  Coppers 

Another  way  of  tinning  the  soldering  copper  is  to  make 
prcssion  in  a  piece  of  sheet  tin  and  place  in  it  a  small 
•  lii.intity  of  soldering  flux  together  with  a  piece  of  solder. 
the  copper  until  bright,  heat  it  to  about  6OO  deg.  F., 
and  then  move  it  around,  while  hot,  in  the  depression  in 
the  tin  until  it  becomes  coated  with  molten  solder.  It  will 
now  IM-  ready  to  use. 

The  n,\t  step  is  to  clean  thoroughly  the  parts  to  be 
joint  d.  using  fine  emery  cloth,  sandpaper  or  a  scraper. 
If  the  parts  are  of  raw  material,  sandpaper  will  do,  but 
if  they  are  old  parts  which  previously  have  been  exposed. 


or  if  a  In  i\ y  ovule  has  formed,  the  surfaces  to  be  soldered 
should  U  iihd  or  script  d  until  jicrfectlv  bright  and  clean. 
The  ,  !  rface  should  then  IK-  covered  with  soldering 

fluid  or  one  of  the  iii.inv    soldering  pa- 

II'  it  the  soldi  ring  copper  to  about  tiOO  deg.  F.,  and 
touch  it  to  (he  solder,  being  careful  to  get  only  a  small 
amount  of  solder  on  the  copper.  Hub  the  copper  over  the 
surfaces  to  lie  joined  until  n  bright,  even  coating  of  solder 
clings  to  the  surfaces.  Place  the  pieces  together  and 
.ntil  the  solder  flows,  using  the  hot  copper  to  furnish 
the  necessary  heat  and  adding  more  solder  as  n. 
Care  irtust  be  taken  not  to  overheat  the  pieces  at  the  joint. 
as  this  has  a  ten.!-  m  v  to  weaken  the  metal  at  that  point 
and  may  cause  trouble. 

The  same  general  procedure  as  the  above  is  followed 
for  hard  soldering,  with  the  exception  that  a  higher  tem- 
perature must  be  applied. 

Fluxes 

1  luxes  arc  used  in  soldering  to  prevent,  so  far  as  pos- 
sible, the  formation  of  oxides  on  the  heated  surfaces,  and 
to  flux  off  those  that  may  have  formed.  Acid  fluxes  are 
the  most  effective  and  on  iron  or  steel  are  practically 
>ary.  The  objection  to  their  use  is  that  unless  the 
parts  are  thoroughly  cleaned  after  soldering  the  acid  in 
the  flux  attacks  and  corrodes  them. 

In  the  case  of  stranded  wires  or  cables  the  flux  will 
penetrate  into  the  minute  spaces  between  the  strands  and 
will  IK-  extremely  difficult  to  remove  or  neutralize,  even 
when  the  cable  or  wire  is  washed  with  or  dipped  in  an 
alkaline  solution,  such  as  soap  or  soda  water. 

Some  of  the  fluxes  in  general  use  are: 

Xinc  chloride  (/n  Cl),  corrosive 

Dilute  muriatic  acid  (H  Cl),  corrosive 

Resin,  non-corrosive.  This  is  satisfactory  for  tin,  but 
will  not  work  on  galvanising. 

Hi-sin  and  sperm  candle  melted  together  make  a  fair 
non-corrosive  paste.  For  either  tin  or  galvanising  use 
three  parts  resin  to  one  part  sperm  candle.  Sometimes 
licttcr  results  are  obtained  on  dirty  surfaces  by  adding 
one  part  alcohol  to  this  mixture. 

Mfllinij  point*  of  tcAdert. —  The  melting  points  of  sol- 
ders composed  of  tin  and  lead  in  various  proportions  are 
as  follows: 


Proportion 

Mrllinp 
Point 

Tin 

Lead 

1     part 
1     part 
1     part 
\\  parts 
6     parts 

.'i  parts 
5  parts 
1    part 
1    part 
1   n«rt 

44H  rfrjr.  F. 

All    <lr(T     1 
llr,r.    K. 

340  drg.  K. 
ffTRdr*.  F. 

A  com|H>sition  of  1  to  I  is  most  commonly  used  for  tin- 
smithing.  For  electrical  work  where  the  solder  i*  used 
in  the  form  of  wire,  a  proportion  of  \\'.2  to  I  or  «  to  1  is 
used. 


CHAPTER  XV 
VALUE  OF  PLYWOOD  IN  AEROPLANE  FUSELAGE  CONSTRUCTION 

BY  LIEUTENANT  STEFANS  D'AMico, 
Italian  Aviation   Mission. 


Recently  aeroplane  construction  has  undergone  some 
very  radical  changes,  in  part  due  to  the  exigencies  caused 
by  the  war,  in  part  to  the  natural  tendency  to  make  a 
more  and  more  organic  machine  out  of  the  aeroplane,  by 
employing  in  its  design  the  same  fundamental  principles 
which  guide  the  design  of  modern  mechanical  devices. 

Often  these  two  conditions  have  coincided  so  as  to  ex- 
pedite the  ultimate  result. 

Of  all  the  parts  of  the  aeroplane,  the  fuselage  has  un- 
doubtedly undergone  the  most  radical  change.  On  the 
one  end  the  development  of  aerodynamics  and  the  neces- 
sity to  get  from  the  aeroplane  the  greatest  speed  coupled 
with  the  greatest  mobility  have  changed  its  form  and  pro- 
portions, and  on  the  other  hand  modern  and  more  practical 
principles  of  construction  have  completely  altered  its 
make-up. 

Until  recently,  the  fuselage  in  all  aeroplanes  consisted 
of  a  frame  suitable  to  withstand  the  stress  and  this  was 
then  covered  with  linen  properly  varnished. 

The  frame  consisted  of  four  longerons,  running  length- 
wise of  the  fuselage  with  struts  and  steel  wires  latticing 
in  both  planes,  vertical  and  horizontal,  so  as  to  divide  it 
into  panels. 

The  joints  of  the  struts  to  the  longerons  were  metallic 
fittings  and  the  proper  tension  in  the  latticing  was  obtained 
by  the  use  of  turnbuckles. 

The  solid  resulting  by  this  method  is  capable  of  with- 
standing the  stresses  imposed  from  all  sides  but  is  a  com- 
plicated structure,  since  it  is  made  up  of  a  large  number 
of  parts,  has  a  great  many  wire  connections,  and  must  be 
frequently  adjusted  to  the  proper  shape  by  giving  the 
wires  the  proper  tension. 

The  fuselage,  because  of  the  frequent  landing,  is  sub- 
jected to  violent  dynamic  stresses  causing  a  stretching  in 
the  tension  wires,  a  disarrangement  of  the  whole  structure, 
as  well  as  a  stretching  of  the  linen  covering.  The  ele- 
ments also  influence  to  a  great  extent  the  stretching  of 
the  covering  and  this  impairs  to  a  large  degree  the  aero- 
dynamic property  of  the  machine. 

The  war  then  has  developed  it  to  such  an  extent,  that 
while  the  fuselage  has  forfeited  a  little  the  advantage  in 
weight,  the  machine  has  gained  in  life  and  efficiency. 

At  any  rate,  the  abandoning  of  such  a  construction  was 
desirable  because  of  the  ever-increasing  scarcity  of  metal 
fittings  of  alloy  steel,  as  well  as  for  the  excessive  cost  and 
the  lack  of  labor  which  is  felt  more  each  day. 

The  use  of  plywood,  which  had  already  been  used  in 
large  quantity  in  the  construction  of  hydroaeroplane  boats, 
appeared  to  be  very  appropriate  since  it  eliminated  a 
great  many  of  the  disadvantages  enumerated. 

In  as  much  as  the  only  advantage  of  the  old  type  was 


its  lightness,  all  the  builders  tried  very  hard  to  make  the 
best  use  possible  of  the  material  in  order  to  eliminate  this 
disadvantage  which,  in  some  cases,  is  considerable. 

In  its  most  common  form  the  modern  fuselage  is  made 
of  four  longerons,  tied  together  by  means  of  diaphragms 
and  then  covered  by  plywood.  The  shearing  stresses  are 
taken  care  of  by  stiffening  the  outside  covering  with  ribs 
of  wood. 

The  transverse  stiffness  is  attained  by  means  of  trans- 
verse diaphragms  in  the  rear,  while  in  the  front,  where 
this  is  not  possible,  since  the  passengers  have  to  be  accom- 
modated as  well  as  the  tanks,  motors,  etc.,  this  is  done  in 
a  special  way  for  each  case,  utilizing  to  the  best  ad- 
vantage the  space  resulting  in  distributing  the  various 
parts  of  the  plane.  The  plywood  is  made  to  resist  the 
moments  due  to  deflection  and  principally  shearing 
stresses.  In  this  way  the  material  is  used  to  its  full 
extent  and  its  strength  utilized  to  the  best  advantage. 
Therefore,  since  the  material  is  used  to  its  full  value,  the 
construction  becomes  light. 

The  maximum  strain  on  the  fuselage  comes  on  it  when 
the  tail  skid  strikes  the  ground.  The  maximum  reaction 
will  naturally  depend  on  the  total  load  P,  which  comes  on 
it  at  this  point  and  in  computing,  it  is  customary  to  con- 
sider this  as  double;  that  is  2P.  (Fig.  1  and  Fig.  2.) 

Therefore,  at  the  section  X  distant  from  the  point  where 
the  load  may  be  considered  as  applied  the  moment. 
>  MX  =  JP.X 

From  this  moment  must  be  deducted  the  moment  due  to 
own  weight  of  the  fuselage  so  that  the  resulting  expres- 
sion will  be 

M'x=ZPx  —  P'x. 

In  its  vertical  direction  the  fuselage  suffers  a  deflecting 
moment  due  to  the  compound  load  coming  on  the  rudder. 

If  this  force  be  denoted  by  P"  then  Mx"~P"  O  -f  c) 
in  which  C  is  the  distance  from  the  axis  of  the  tail  and  the 
center  of  pressure  of  the  surface  which  makes  up  the  rud- 
der. 

Considering  the  ordinary  quadrangular  form  of  fuse- 
lage, the  distance  Hx  between  the  centers  of  gravity  of 
the  upper  and  lower  longeron  of  the  section  H'jc  of  the 
longerons  may  be  considered  variable  and  following  the 
linear  law.  So  that: 


hx  =  ho 


&i  —  ho 


oc  x;  oc  = 


I 


Also  in  the  horizontal  section  the  distance  A.r  between 
the  centers  of  gravity  of  the  sections  of  the  longerons  may 
be  considered  in  the  same  way  as  varying  with  straight 
line  law. 


312 


PLYWOOD  IN   .\F.KoiM..\M.   PUSELAGI    CONSTR1  CTIOH  :n.. 


Imill 
or  inlrrior 


Cfou 


r.in~MTsc   jririli-r  >r<-ti<uis   Imill    fur   llnrriiu  of 
Naval  Const  ruction  and   Kepair 


^ 


Ti-stinjr   I'rrsv  in 
IjilMirntory 


Knjrinc    Ivnrrrs    for    LiU-rlv    inoliirrd    DrMnvi- 
land    lours 


Cowling  and  iiftcr-deck  covering,  built  of  p1jr-wmxl,  for  Dcllnvil/ind  Koura. 


Photo,   rourtnjr  of  Ib*    Dodf*   Mf(    <'•• 
Interiors  of  aeroplane  ronstrurtion  rooms  in  an  American  factory 


314 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


Therefore  in  the  same  way  we  would  have 
Ao 

2  Wx  [Ao 


I 


r        -I 

J        —    = 

L  #  J, 


2 


Therefore  at  the  longeron,  with  the  greatest  stress  we 
will  have  the  following  united  stress 

M'x  M"x 

So  =  8,  +  S2  =  -  +  - 

2Wa[ho+*x]        2  Wx  [Ao  +  j8«] 
from  which  would  follow 

M's  M"x 


28o  [Ao  +  ccj-]         28o[Ao  +  /3x] 

If  we  fix  So  from  the  quality  of  the  wood  employed,  and 
the  factor  of  safety  sought,  the  values  <x,  /8,  Ao,  ho  will 
also  be  determined  so  that  the  required  section  of  the  ma- 
terial will  be  obtained. 

In  order  to  find  this  section  it  is  necessary  to  determine 
to  what  extent  the  plywood  covering  helps  to  resist  the 
stresses. 

Tests  which  have  been  made  have  shown  that  the  sec- 
tion Wx  may  be  considered  as  made  up  of  the  longeron 
m,  n,  r,  s  and  of  a  portion  A,  B,  C  -  -  A,  D,  E  of  the  cov- 
ering working  in  conjunction  with  the  longeron  itself  and 
utilizing  DE  and  BC  may  be  considered  equal  to  20.S, 
where  S  is  the  thickness  of  the  plywood.  (Fig.  3.) 
.  :  .  Wx  may  be  obtained  from  the  formula 

—  2 

Wx=[h  XI]  +2X  20.5 

In  calculating  the  shearing  stresses  it  is  best  to  plot 
them.  This  evidently  will  depend  on  the  distribution  of 
the  strains  along  the  fuselage.  Having  once  determined 
from  such  diagrams  the  value  of  the  reaction  T,  and  the 
sectional  area  on  which  this  acts,  it  may  be  considered 
that  one-half  of  this  reaction  will  be  taken  care  of  by  the 
plvwood  acting  in  tension  and  the  other  half  by  the  diag- 
onal bracing  at  the  sides  which  stiffens  the  structure. 

Therefore  the  stress  on  the  plywood  will  be: 


8  = 


h  [2  X  S] 

For  the  stress  in  the  diagonals,  it  will  be  easy  to  find  the 
value  along  the  diagonal  in  compression  which  we  will  call 
7\  (this  value  being  for  both  diagonals). 

The  minimum  moment  of  inertia  will  be  (Fig.  -1) 

-2 
S 

Ixo  =  Ix  —  • — 
A 

where  S  is  static  moment  of  the  section  with  respect  to 
XX,  and  A  the  area  of  section  of  the  diagonal  as  well  as 
that  of  the  plywood  acting  with  it. 

The  diagonals  may  be  considered  as  being  completely 
fixed  at  both  ends.  Therefore  it  will  be  easy  to  determine 
the  stress  at  the  proposed  section. 

The  more  detailed  and  exact  is  the  analysis  of  the 
stresses  made,  the  more  advantageously  will  the  material 
be  utilized  resulting  in  a  great  saving  of  weight. 

The  plywood  fuselage  which  has  already  found  com- 
plete use  in  the  small  and  medium  sized  machines  has  en- 
countered some  difficulty  in  the  large  machines  and  this 
because  of  the  large  resulting  weight.  However,  it  may 
be  foreseen  that  in  the  very  near  future,  these  difficulties 
will  be  eliminated. 

Recently  tests  have  been  conducted  on  fuselages  made 
of  wood,  in  which  the  longitudinal  longerons  running  the 
full  length  of  the  fuselage  have  been  eliminated  as  well  as 
the  stiffening  ribs. 

Such  a  fuselage  would  be  made  by  moulding  on  mould 
representing  the  fuselage  very  thin  sheets  of  wood  with 
fibre  running  perpendicular  to  one  another,  and  then  re- 
moving the  shell  from  the  mould  when  completed. 

These  tests  have  already  given  good  results  and  it 
seems  as  though  they  will  lead  to  a  practical  result  which 
would  bring  a  great  advantage  in  weight. 


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III 


CHAPTER  XVI 
NOMENCLATURE  FOR  AERONAUTICS 


AERODYNAMICS— The  science  which  treats  of  the  air  or 
other  gaseous  bodies  under  the  action  of  forces  and 
of  their  mechanical  effects. 

AEROFOIL  —  A  thin  wing-like  structure,  flat  or  curved,  de- 
signed to  obtain  reaction  upon  its  surfaces  from  the 
air  through  which  it  moves. 

AERONAUTICS  —  That  branch  of  engineering  which  deals 
with  the  design,  construction  and  operation  of  air 

craft. 

AILERON  —  A  movable  auxiliary  surface  used  for  the  coi 
trol  of  rolling  motion  of  an  aeroplane,  i.  e.,  rotation 
about  its  fore  and  aft  axis. 

AIRCRAFT  — Any  form  of  craft  designed  for  the  navi- 
gation of  the  air;  aeroplanes,  balloons,  dirigibles, 
helicopters,  kites,  kite  balloons,  ornithopters,  gliders, 

etc. 
AERODROME  —  The  name  usually  applied  to  a  ground  and 

buildings  used  for  aviation. 

AEROPLANE  —  A  form  of  aircraft  heavier  than  air,  which 
has  wing  surfaces  for  sustentation,  stabilizing  sur- 
faces, rudders  for  steering,  power  plant  for  propul- 
sion through  the  air  and  some  form  of  landing  gear; 
either  a  gear  suitable  for  rising  from  or  alighting  on 
the  ground,  or  pontoons  or  floats  suitable  for  alight- 
ing on  or  rising  from  water.  In  the  latter  case,  the 
term  "  Seaplane  "  is  commonly  used.  (See  defini- 
tion.) 

pusher  —  A  type  of  aeroplane  with  the  propeller  or  pro- 
pellers in  the  rear  of  the  wings. 
Tractor  —  A  type  of  aeroplane  with  the  propeller  or 

propellers  in  front  of  the  wings. 

Monoplane  —  A  form  of  aeroplane  whose  main  sup- 
porting surface  is  disposed  as  a  single  wing  extend- 
ing equally  on  each  side  of  the  body. 
Biplane  —  A  form  of  aeroplane  in  which  the  main  sup- 
porting surface  is  divided  into  two  parts,  one  above 
the  other. 

Triplane  —  A  form  of  aeroplane  whose  main  support- 
ing surface  is  divided  into  three  parts,  superimposed. 
Multiplane  —  An  aeroplane  the  main  lifting  surface  of 
which  consists  of  numerous  surfaces  or  pairs  of  su- 
perimposed wings. 

One  and  One-Half  Plane  —  A  biplane  in  which  the 
span  of  the  lower  plane  is  decidedly  shorter  than 
that  of  the  upper  plane. 

Flyiny  Boat  —  An  aeroplane  fitted  with  a  boat-like  hull 
suitable  for  navigation  and  arising  from  or  alighting 
on  water. 
Seaplane  —  An  aeroplane  fitted  with  pontoons  or  floats 

suitable  for  alighting  on  or  rising  from  the  water. 
AIR  POCKET  —  A  local  movement  or  condition  of  the  air 

316 


causing  an  aeroplane  to  drop  or  lose  its  correct  atti- 
tude. 

AIR  SPEED  METER  —  An  instrument  designed  to  measun 
the  velocity  of  an  aircraft  with  reference  to  the  air 
through  which  it  is  moving. 

ALTIMETER  —  An  instrument  mounted  on  an  aircraft  to 
continuously  indicate  its  height  above  the  surface  of 
the  earth. 

ANEMOMETER  —  An  instrument  for  measuring  the  velocity 
of  the  wind  or  air  currents  with  reference  to  the 
earth  or  some  fixed  body. 

ANGLE  OF  ATTACK  —  The  acute  angle  between  the  direc- 
tion of  relative  wind  and  the  chord  of  an  aerofoil,  i.  e., 
the  angle  between  the  chord  of  an  aerofoil  and  its 
motion  relative  to  the  air.  (This  definition  may  be 
extended  to  any  body  having  an  axis.) 
Best  Climbing  —  The  angle  of  attack  at  which  an  aero- 
plane ascends  fastest.  An  angle  about  half  way  be- 
tween the  maximum  and  optimum  angle. 
Critical  — The  angle  of  attack  at  which  the  lift  is  a 
maximum,  or  at  which  the  lift  curve  has  its  first 
maximum;  sometimes  referred  to  as  the  "burble 
point."  (If  the  lift  curve  has  more  than  one  maxi- 
mum, this  refers  to  the  first  one.) 

Gliding  —  The  angle  the  flight  path  makes  with  the 
horizontal  when  flying  in  still  air  under  the  influence 
of  gravity  alone,  i.  e.,  without  power  from  the  en- 
gine. 

Maximum  —  The  greatest  angle  of  attack  at  which,  for 
a  given  power,  surface  and  weight,  horizontal  flight 
can  be  maintained. 

Minimum  —  The  smallest  angle  of  attack  at  which,  for 
a  given  power,  surface  and  weight,  horizontal  flight 
can  be  maintained. 
Optimum  —  The  angle  of  attack  at  which  the  lift-drift 

ratio  is  the  highest. 

ANGLE  OF  INCIDENCE  (Rigger's  Angle)  — The  angle  be- 
tween the  longitudinal  axis  of  the  aeroplane  and  the 
chord  of  an  aerofoil. 

APPENDIX  —  The  hose  at  the  bottom  of  a  balloon  used  for 
inflation.  In  the  case  of  a  spherical  balloon  it  also 
serves  for  equalization  of  pressure. 

ASPECT  RATIO  —  The  ratio  of  span  to  chord  of  an  aerofoil. 
AVIATOR  —  The  operator  or  pilot  of  heavier-than-air  craft, 
This  term  is   applied   regardless   of  the   sex   of  the 
operator. 
AVION  —  The  official  French  term  for  military  aeroplane; 

only. 

AXES  OF  AN  AIRCRAFT  — The  three  fixed  lines  of  refer- 
ence; usually  passing  through  the  center  of  gravitj 
and  mutually  rectangular.  The  principal  axis  in  : 


NO.MKM  I.ATl   ]{K   10R    AKKONAI   Tit  s 


817 


forr  .-Hid  aft  direction,  iisuallx  parallel  tu  (lit-  axis  of 
tin  propeller  and  in  tin-  plane  of  s\  mmetri  .  is  tin- 
Longitudinal  Axis  or  the  lor.  and  Alt  Axis  The 
axis  perpendicular  to  this  anil  in  tin  plain  of  ,\m 
nietry  is  the  Vertieal  Axis;  the  third  axis  perpendicu- 
lar to  the  other  two  is  the  Lateral  Axis,  also  called  the 
Tr  IIISM  rse  Axis  or  the  Athwartship  Axis.  In  miithe 
niatieal  diseiission  the  first  of  these  axes,  drawn  from 
Iron!  to  nar  is  called  the  \  Axis;  tin-  si  rond,  drawn 
upward,  the  /  Axis;  and  the  third,  forming  a  "  left- 
liandi-d  "  s\  stem,  tin  Y  Axis 

B.U.\MMI  <  ovnioi.  Si  HFACE —  A  type  of  surface  se- 
etired  liy  adding  area  forward  of  the  axis  of  rota- 
tion. In  an  airstrcam  a  force  is  excrtid  on  this 
.id  !•  d  an  a.  tending  to  aid  in  the  movement  about  the 
axis. 

H\i  \NIIN..   I  LAPS — (See  AILERON.) 

ISwinSKT —  A  small  balloon  within  the  interior  of  a 
balloon  or  diri^ihle  for  the  purpose  of  controlling 
the  ascent  or  de.sci  nt.  and  for  maintaining  pressure 
on  the  outer  envelope  so  as  to  prevent  deformation. 
The  ballonet  is  kept  inflated  with  air  at  the  required 
pressure,  under  the  control  of  a  blower  and  valves. 

BALLOON  —  A  form  of  aircraft  comprising  a  gas  bag  and 
a  basket  and  supported  in  the  air  by  the  buoyancy  of 
the  gas  contained  in  the  gas  bag,  which  is  lighter 
than  the  amount  of  air  it  displaced;  the  form  of  the 
gas  bag  is  maintained  by  the  pressure  of  the  contained 
gas. 
Barrage  —  A  small  spherical  captive  balloon,  raised  as  a 

protection  against  attacks  by  aeroplanes. 
('attire  —  A    balloon    restrained    from    free    flight    by 

means  of  a  cable  attaching  it  to  the  earth. 
Kite  —  An  elongated  form  of  captive  balloon,  fitted  with 
tail  appendages  to  keep  it  headed  into  the  wind,  and 
deriving  increased  lift  due  to  its  axis  being  inclined 
to  the  wind. 
Pilot  —  A  small  spherical  balloon  sent  up  to  show  the 

direction  of  the  wind. 

Soundiny  —  A  small  spherical  balloon  sent  aloft,  with- 
out passengers,  but  with  registering  meterological  in- 
struments for  recording  atmospheric  conditions  at 
high  altitudes. 

BALLOON  —  DIRKIIBLE  —  A  form  of  balloon  the  outer  en- 
velope of  which  is  of  elongated  horizontal  form,  pro- 
vided with  a  car,  propelling  system,  rudders  and 
stabilizing  surfaces.  Dirigibles  are  divided  into 
three  classes:  Rigid,  Semi-rigid  and  Non-rigid.  In 
the  Rigid  type  the  outer  covering  is  held  in  place 
and  form  by  a  rigid  internal  frame  work  and  the 
shape  is  maintained  independently  of  the  contained 
gas.  The  shape  nnd  form  of  the  Semi-rigid  type  is 
maintained  partly  by  an  inner  framework  and  partly 
by  the  contained  gas.  The  Non-rigid  type  is  held  to 
form  entirely  by  the  pressure  of  the  contained  gas. 

HW.LOON  BED  —  A  mooring  place  on  the  ground  for  a 
captive  balloon. 

BALLOON  CLOTH  —  The  cloth,  usually  cotton,  of  which 
balloon  fabrics  arc  made. 

BALLOON  FABRIC  —  The  finished  material,  usually  rub- 
berized, of  which  balloon  envelopes  are  made. 

BANK  —  To  incline  an  aeroplane  laterally,  i.  e.,  to  rotate 


it  al'out  the  fore-and-aft  axis  when  making  a  turn. 
Right  li-ink  is  to  incline  the  aeroplane  with  the  right 
win^r  down.  Also  usi  d  as  a  noun  to  di  si-rilie  tin- 
position  ni  an  aeroplane  when  its  lateral  axis  is  in- 
clined to  the  horixontal. 

BAROGRAPH  —  An  instrument  for  recording  xariatmns  in 
barometric  pressure.  In  aeronautics  the  charts  on 
which  the  records  are  made  are  prepared  to  indicate 
altitudes  directly  instead  of  barometric  pressure,  in- 
asmuch as  the  atmospheric  pressure  varies  almost 
directly  with  the  altitude. 

BAROMETER —  An  instrument  for  measuring  the  pressure 
of  the  atmosphere. 

BANKET  —  The  i-ar  suspended  beneath  the  balloon  for 
passengers,  ballast,  etc. 

BIPLANE — (See  AEROPLANE.) 

BODY    (or   AN   AEROPLANE)  —  A   structure,   usually    <  n 
closed,   which   contains   in   a   streamline   housing  the 
powcrplant,  fuel,  passengers,  etc. 

Fuirlage  —  A  type  of  body  of  streamline  shape  carry- 
ing the  empannage  and  usually  forming  the  main 
structural  unit  of  an  aeroplane. 

Monocoque  —  A  special  type  of  fuselage  constructed  of 
metal  sheeting  or  laminated  wood.  A  monocoque  is 
generally  of  circular  or  elliptical  cross-section. 
\acelle  —  A  type  of  body  shorter  than  a  fuselage.  It 
does  not  carry  the  empannage.  but  acts  more  as  • 
streamline  housing.  Usually  used  on  a  pusher  type 
of  machine. 

Hull — A  boat -like  structure  which  forms  the  body  of 
a  flying-boat. 

BONNET  —  The  appliance,  having  the  form  of  a  parasol, 
which  protects  the  valve  of  a  spherical  balloon  against 
rain. 

BOOM  —  (See  OUTRIGGER.) 

BOWDEN  WIRE  —  A  stiff"  control  wire  enclosed  in  a  tube 
used  for  light  control  work  where  the  strain  is  com- 
paratively light,  as  for  instance  throttle  and  spark 
controls,  etc. 

BOWDEN  WIRE  GUIDE  —  A  elose  wound,  spring-like,  flex- 
ible guide  for  Bowden  wire  controls. 

BRIDLE  —  The  system  of  attachment  of  cables  to  a  balloon, 
including  lines  to  the  suspension  band. 

BULLS  EYES  —  Small  rings  of  wood,  metal,  etc.,  forming 
part  of  balloon  rigging,  used  for  connection  or  ad- 
justment of  ropes. 

BURBLE  POINT — (See  ANGLE  —  CRITICAL.) 

CABANE  (OR  CABANC  STRUT)  —  In  a  monoplane,  the  strut 
or  pyramidal  frame  work  projecting  above  the  body 
and  wings  and  to  which  the  stays,  ground  wires, 
braces,  etc.,  for  the  wing  arc  attached. 

In  a  biplane,  the  compression  member  of  an  auxili- 
ary truss,  serving  to  support  the  overhang  of  the 
upper  wing. 

CAMBER  —  The  convexity  or  rise  of  the  curve  of  an  aero- 
foil from  its  chord,  usually  expressed  as  the  ratio  of 
the  maximum  departure  of  the  curve  from  the  chord 
as  a  fraction  thereof.  Top  Camhrr  refers  to  the  top 
surface  and  Bottom  Camber  to  the  bottom  surface  of 
an  aerofoil.  Mean  Cambrr  is  the  mean  of  these  two. 

CAPACITY-CARRYING  —  The  excess  of  the  total  lifting  ca- 
pacity over  the  dead  load  of  an  aircraft.  The  latter 


318 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


includes  structure,  power  plant  and  essential  acces- 
sories. Gasoline  and  oil  are  not  considered  essential 
accessories. 

The  cubic  contents  of  a  balloon. 
CAPACITY-LIFTING—  (See  LOAD)  —  The  maximum  flying 

load  of  an  aircraft. 
CATHEDRAL  —  A  negative  dihedral. 
CEILING  —  The   maximum    possible    altitude   to   which    a 

given  aeroplane  can  climb. 

CENTER  —  The  point  in  which  a  set  of  effects  is  assumed 
to  be  accumulated,  producing  the  same  effect  as  if 
all  were  centered  at  this  point. 

There  are  five  main  centers  in  an  aeroplane  — 
Center  of  Lift,  Center  of  Gravity,  Center  of  Thrust, 
Center  of  Drag  and  Center  of  Keelplane  Area.  The 
latter  is  also  called  the  Directional  Center.  The  sta- 
bility, controllability  and  general  air  worthiness  of 
aeroplane  depend  largely  on  the  proper  positioning 
of  these  centers. 

CENTER  OF  PRESSURE  OF  AN  AEROFOIL  —  The  point  in  the 
plane  of  the  chords  of  an  aerofoil,  prolonged  if  neces- 
sary, through  which  at  any  given  attitude  the  line 
of  action  of  the  resultant  air  force  passes.  (This 
definition  may  be  extended  to  any  body.) 
CENTER  PANEL  — The  central  part  of  the  upper  wing  (of 
a  biplane)  above  the  fuselage.  The  upper  wings  are 
attached  to  this  on  either  side. 

CHORD  —  (Of  an  aerofoil  section.)  A  straight  line  tan- 
gent to  the  under  curve  of  the  aerofoil  section,  front 
and  rear. 

CHORD  LENGTH  —  (Or  length  of  Chord.)  —  The  length 
of  an  aerofoil  section  projected  on  the  chord,  extended 
if  necessary. 

CLINOMETER —  (See  INCLINOMETER.)  _ 

CLOCHE  —  The  bell-shaped  construction  which  forms  the 

lower  part  of  the  pilot's  control  lever  in  the  Bleriot 

control  and  to  which  the  control  cables  are  attached. 

COCKPIT  —  The  space  in  an   aircraft  body   occupied  by 

pilots  or  passengers. 
CONCENTRATION  RING  —  The  hoop  to  which  are  attached 

the  ropes  suspending  the  basket  (of  a  balloon). 
CONTROLS  —  A  general   term   applied   to   the   mechanism 
used  to  control  the  speed,  direction  of  flight  and  alti- 
tude of  an  aircraft. 

Bridge  (Deperdussin-"  Dep  "  Control)  —  An  inverted 
"  U  "  frame  pivoted  near  its  lower  points,  by  which 
the  motion  of  the  elevators  is  controlled.  The  ailer- 
ons are  controlled  by  a  wheel  mounted  on  the  upper 
center  of  this  bridge. 
Dual  —  Two  sets  of  inter-connected  controls  allowing 

the  machine  to  be  operated  by  one  or  two  pilots. 
Shoulder  —  A  yoke  fitting  around  the  shoulders  of  the 
pilot  by  means  of  which  the  ailerons  are  operated  (by 
the  natural  side  movement  of  the  pilot's  body)  to 
cause  the  proper  amount  of  banking  when  making  a 
turn  or  to  correct  excessive  bank.  (Used  on  early 
Curtiss  planes.) 

Stick  (Joy-stick)  —  A  vertical  lever  pivoted  near  its 
lower  end  and  used  to  operate  the  elevators  and 
ailerons. 

COWLS  —  The  metal  covering  enclosing  the  engine  section 
of  the  fuselage. 


CHOW'S  FOOT  —  A  system  of  diverging  short  ropes  for  dis- 
tributing the  pull  of  a  single  rope.  (Used  princi- 
pally on  balloon  nets.) 

DECALAGE  —  The  difference  in  the  angular  setting  of  the 
chord  of  the  upper  wing  of  a  biplane  with  reference 
to  the  chord  of  the  lower  wing. 

DIHEDRAL  (In  an  aeroplane)  —  The  angle  included  at  the 
intersection  of  the  imaginary  surfaces  containing  the 
chords  of  the  right  and  left  wings  (continued  to  the 
planes  of  symmetry  if  necessary).  This  angle  is 
measured  in  a  plane  perpendicular  to  that  intersec- 
tion. The  measure  of  the  dihedral  is  taken  as  90 
deg.  minus  one-half  of  this  angle  as  defined. 

The  dihedral  of  the  upper  wing  may  and  frequently 
does  differ  from  that  of  the  lower  wing  in  a  biplane. 
Lateral  —  An  aeroplane  is  said  to  have  lateral  dihedral 
when  the   wings   slope   downward   from   the   tips   to- 
ward the  fuselage. 

Longitudinal  —  The  angular  difference  between  the  an- 
gle of  incidence  of  the  main  planes  and  the  angle 
of  incidence  of  the  horizontal  stabilizer. 
DIRIGIBLE  —  A  form  of  balloon,  the  outer  envelope  of 
which  is  of  elongated  horizontal  form,  provided  with 
a  propelling  system,  car,  rudders  and  stabilizing  sur- 
faces. 

Non-Rigid  —  A  dirigible  whose  form  is  maintained  by 
the  pressure  of  the  contained  gas  assisted  by  the  car 
suspension  system. 
Rigid  —  A  dirigible  whose  form  is  maintained  by  a  rigid 

structure  contained  within  the  envelope. 
Semi-rigid  —  A  dirigible  whose  form  is  maintained  by 

means  of  a  rigid  keel  and  by  gas  pressure.. 
DIVING  RUDDER  —  (See  ELEVATOR.) 

DOPE  —  A  preparation,  the  base  of  which  is  cellulose 
acetate  or  cellulose  nitrate,  used  for  treating  the 
cloth  surfaces  of  aeroplane  members  or  the  fabric  of 
balloon  gas  bags.  It  increases  the  strength  of  the 
fabric,  produces  tautness,  and  acts  as  a  filler  to  make 
the  fabric  impervious  to  air  and  moisture. 
DRAG  —  The  component  parallel  to  the  relative  wind  of 
the  total  force  on  an  aircraft  due  to  the  air  through 
which  it  moves. 

That  part  of  the  drag  due  to  the  wings  is  called 
"Wing  Resistance"  (formerly  called  "Drift"); 
that  due  to  the  rest  of  the  aeroplane  is  called  "  Para- 
site Resistance"  (formerly  called  head  resistance). 
The  total  resistance  to  motion  through  the  air  of 
an  aircraft,  that  is,  the  sum  of  the  drift  and  parasite 
resistance.  Total  Resistance. 

DRIFT  —  The  component  of  the  resultant  wind  pressure 
on  an  aerofoil  or  wing  surface  parallel  to  the  air 
stream  attacking  the  surface. 

Also  used  as  synonymous  with  lee-way. 
(See  DRAG.) 

DRIFT  INDICATOR  —  An  instrument  for  the  measurement 
of  the   angular  deviation   of  an  aircraft   from   a   set 
course,  due  to  cross  winds. 
Also  called  Drift  Meter. 

DRIFT  WIRES  —  Wires  which  take  the  drift  load  and  trans- 
fer it  through  various  members  to  the  body  of  the 
aeroplane. 
DRIP  CLOTH  —  A  curtain  around  the  equator  of  a  balloon 


NOMI.M  1, ATI  UK    1  (»K    A  KK<  >N  A  I   TU  s 


which    prexents    rain    from   dripping   intu   tin     basket. 
DROOP  — 

(a)    An  aileron  is  said   to  h.-uc  droop  when  ii    ,.          .  • 
justed  tin!  its  trailing  edge  is  In  low  tin-  trilling  edge 
of  tin    in  nil   plane. 

(6)  When  :i  winy  is  warped  In  gixe  wash  out  or  wash  ill, 
its  trailing  edge  will.  relatue  to  the  le  iding  edge,  be 
displaced  progressively  from  on>  .  n.i  to  tin-  otlu-r. 
A  downward  displaeeneBi  is  called  droop. 

.IK.XXTOH        A  hinged  surface,  usually   in   tin-   form  of  a 
hormuit.il   niddi-r.  inoiintcd  nt  the  tail  of  an  aircraft 
for   controlling   tin-   longitudinal   attitiulc   of   tin-   air- 
craft, i.  r..  it-,  rotation  about   tin-  lateral  a\is. 
K \n-\\\  M.I         A  term  applied  to  the  tail  group  of  parts 
in  aeroplane. 

-  •   Txn..) 

'.M.iNt    SIM.   BKARERS,  STPPORTS —  The  members  form- 
mi:  tin-  engine  lied. 

NHIIIM.  F.IM.K        The  foremost  part  or  forward  edge  of 
an  arrofoil  or  propeller  blade. 

•  ri         The  portion  of  the  balloon  or  dirigible  which 
contains   the 
'.grxroR  —  The  largest  horizontal  circle  of  a  spherical 

balloon 

•'xiuiNi.        A  wood  or  metal  form  attached  to  the  rear  of 
struts,  braces  or  wires  to  give  them  a  streamline  shape. 
;"'AIH  LEAD  —  A  guide  for  a  cable. 

FIN —  A  small  fixed  aerofoil  attached  to  part  of  an  air- 
craft to  promote  stability;  for  example,  tail  fin,  skid 
tin.  ete.  Fins  may  be  either  horizontal  or  vertical 
and  are  often  adjustable. 

STXHII.IXER.) 
>'IKK   D\MI    —A  metal  screen  dividing  the  engine  section 

of  an  aeroplane  body  from  the  cockpit  section. 
jFi.n.iiT  PATH  —  The  path  of  the  center  of  gravity  of  an 

aircraft  with  reference  to  the  earth. 

'i.o\  r  — That  portion  of  the  landing  gear  of  an  aircraft 
which    provides   buoyancy  when   it  is   resting  on   the 
surface  of  the  water. 
i>Lvi\(.   HOAT — (See  AEROPLANE.) 

•'LXIM;  POSITION  —  The  position  of  a  machine,  assumed 
when   (lying  horizontally   in   still   air.     When   on  the 
ground  the  machine  is  placed  in  a  flying  posi:ion  by 
leveling  both  longitudinally  and  laterally.     The  two 
longerons,  engine   sills  or  other  perpendicular  parts 
designated  by  the  maker  are  taken  as  reference  points 
from  which  to  level. 
OOT  BAR  —  (See  RrnnER  BAH.) 
i  M;E  —  (See  BODY.) 

I.AI.K  COVER  —  A  cover  placed  on  a  fuselage  to  pre- 
serve a  streamline  shape. 
JAP  —  The   shortest    distance  between  the  planes  of  the 

chords  of  the  upper  and  lower  wings  of  a  biplane. 
>x-  li  xo —  (See  ENVELOPE.) 

-  To  fly  without  power  and  under  the  influence  of 
gravity  alone. 

—  A  form  of  aircraft  similar  to  an  aeroplane  but 
without  any  power  plant. 

When  utilized  in  variable  winds  it  makes  use  of 
the  soaring  principles  of  flight  and  is  sometimes  called 
a  snaring  machine. 

ANGLE —  (See  ANGLE.) 


(MINK  —  One  ot  tin-  segments  of  fabric  comprising  t' 
I"    of  a  balloon. 

( linn  \n   l  to  MI        (    nix  as  placed  mi   the   |  pro 

i  balloon. 

l(»ri  A  long  trailing  rope  alt  irlicd  to  •  spherical 
balloon  or  dirigible  to  serve  as  a  brake  and  as  a  vari- 
able ballast. 

GfY  —  A  rope,  chain,  wire  ,.r  rod  attached  to  an  objr.t 
t»  -•  .  .  "r  sti  iily  it,  such  as  guys  to  wing,  tail  or 
landing  gear. 

1 1  xMiAB  —  An  aeroplane  si 

HEAD  KK-I.-TANCE —  (See  PARASITE  RKMSTANCB.) 

HELICOPTBR  —  A  form  of  aircraft  whose  support  in  the 
air  i.s  derived  from  the  vertical  thrust  of  prop- lit  rs. 

HORN-CONTROL  ARM  —  An  arm  at  right  angles  to  a  con- 
trol surface  to  which  a  control  cable  i,  attach,  d.  for 
example,  aileron  horn,  rudder  horn,  elevator  horn, 
ete.  Yore  commonly  called  a  Mail. 

Ill- 1. 1.         t  See  Honv.) 

IN<  :  INOMKTEH  —  An  instrument   for  measuring  the  angle 

made  by  the  axis  of  an  aircraft  with  the  horizontal. 
hiiliralor-Hankinff  —  An  inclinometer  indicating  lateral 
inclination  or  bank. 

INSPECTION  WINDOW  —  A  small  transparent  window  in 
the  eim  lope  of  a  balloon  or  in  the  wing  of  an  acr,. 
plane  to  allow  inspection  of  the  interior,  or  of  aileron 
controls  when  the  latter  are  mounted  inside  an  aero 
foil  section. 

INSTABILITY  —  An  inherent  condition  of  a  body,  which, 
if  tin-  body  is  distributed,  causes  it  to  move  toward 
a  position  away  from  its  first  position,  instead  of 
returning  to  a  condition  of  equilibrium. 

KEEL  PLANE  AREA  —  The  total  effective  area  of  an  air- 
craft which  acts  to  prevent  skidding  or  side  slipping. 

KITE  —  A  form  of  aircraft  without  other  propelling  menus 
than  the  tow-line  pull,  whose  support  is  derived  from 
the  force  of  the  wind  moving  past  its  surfaces. 

LANDING  GEAR  —  The  understructure  of  an  aircraft  de- 
signed to  carry  the  load  when  resting  on.  or  running 
on,  the  surface  of  the  land  or  water. 

LEADING  EDGE — (See  KNTKHISI;  KIIOK.) 

LEEWAY  —  The  angle  of  deviation  from  a  set  course  over 
the  earth,  due  to  cross  currents  of  wind.  Also  called 
Drift. 

LIFT  —  The  component  of  the  force  due  to  the  air  pres- 
sure of  an  aerofoil  resolved  perpendicular  to  the 
flight  path  in  a  vertical  plane. 

LIFT  BRACING —  (See  STAY.) 

LIFT-DRIFT  RATIO  —  The  proportion  of  lift  to  drift  is 
known  as  the  lift-drift  ratio.  It  expresses  the  effi- 
ciency of  the  aerofoil. 

LOAD  — 

Draii  —  The  structure,  power  plant  and  essential  acces- 
sories of  an  aircraft. 

fill  —  The  maximum  weight  which  an  aircraft  can 
support  in  flight;  the  gross  weight. 

1'irful  —  The  excess  of  the  full  load  over  the  dead 
weight  of  the  aircraft  itself,  i.  e.,  over  the  weight  of 
its  structure,  power  plant  and  essential  accessories. 
(These  last  must  be  specified.) 

(See  Capacity.) 
LOADING  — The  weight  carried   by   an  aerofoil,   usually 


320 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


expressed  in  pounds  per  square   foot  of  superficial 
area. 

LOBES  —  Bags  at  the  stern  of  an  elongated  balloon  de- 
signed to  give  it  directional  stability. 

LONGERON  —  The  principal  fore-and-aft  structural  mem- 
bers of  the  fuselage  or  nacelle  of  an  airplane. 
(See  LONGITUDINAL.) 

LONGITUDINAL  —  A  fore-and-aft  member  of  the  framing 
of  an  aeroplane  body,  or  of  the  float  in  a  seaplane, 
usually  continuous  across  a  number  of  points  of  sup- 
port. 

LONGITUDINAL  DIHEDRAL — (See  DIHEDRAL.) 

MAST — (See  HORN.) 

MONOCOQUE  —  (See  BODY.) 

MONOPLANE  —  A  form  of  aeroplane  whose  main  support- 
ing surface   is  a   single  wing  extending  equally   on 
each  side  of  the  body. 
(See  AEROPLANE.) 

MOORING  BAND  —  The  band  of  tape  over  the  top  of  a 
balloon  to  which  are  attached  the  mooring  ropes. 

NACELLE —  (See  BODY.) 

NET  —  A  rigging  made  of  ropes  and  twine  on  spherical 
balloons,  which  supports  the  entire  load  carried. 

NOSE  DIVE  —  A  dangerously  steep  descent,  head  on. 

NOSE  PLATE  —  A  plate  at  the  nose  or  front  end  of  the 
fuselage  in  which  the  longerons  terminate. 

NOSE  SPIN  —  A  nose  dive  in  which  the  aeroplane  rotates 
about  its  own  axis  due  to  the  reaction  from  the  pro- 
peller. It  usually  results  from  failure  to  shut  off 
the  engine  in  time  when  going  into  a  nose  dive,  and 
is  likely  to  cause  complete  loss  of  control. 

ORNITHOPTER  —  A  form  of  aircraft  deriving  its  support 
and  propelling  force  from  flapping  wings. 

OUT-RIGGER  —  Members,  independent  of  the  body,  ex- 
tending forward  or  to  the  rear  and  supporting  con- 
trol or  stabilizing  surfaces: 

OVERHANG  —  The  distance  the  wings  project  out  beyond 
the  outer  struts. 

PAN  CAKE,  To  —  To  descend  as  a  parachute  after  a  ma- 
chine has  lost  forward  velocity.  To  strike  the 
ground  violently  without  much  forward  motion. 

PANEL —  A  portion  of  a  framed  structure  between  adja- 
cent posts  or  struts.  Applied  to  the  fuselage  it  is 
the  area  bounded  by  two  struts  and  the  longerons. 
An  entire  wing  is  often  spoken  of  as  a  panel.  Thus 
the  upper  lifting  surface  of  a  biplane  is  usually  of 
three  parts  designated  as  the  right  upper  panel,  left 
upper  panel  and  the  center  panel. 

PARACHUTE  — •  An  apparatus  made  like  an  umbrella  used 
to  retard  the  descent  of  a  falling  body. 

PARASITE  RESISTANCE  —  The  total  resistance  to  motion 
through  the  air  of  all  parts  of  an  aircraft  not  a  part 
of  the  main  lifting  surface. 

PATCH  SYSTEM  —  A  system  of  construction  in  which 
patches  or  adhesive  flaps  are  used  in  place  of  the 
suspension  band  in  a  balloon. 

PERMEABILITY  —  The  measure  of  the  loss  of  gas  by  diffu- 
sion through  the  intact  balloon  fabric. 

PHILLIPS  ENTRY  —  A  reverse  curve  on  the  lower  surface 
of  an  aerofoil,  towards  the  entering  edge,  designed 
to  more  evenly  divide  the  air. 

PITCH  —  OF  A  PROPELLER —  (See  PROPELLER.) 


PITCH  —  OF  A  SCREW  —  The  distance  a  screw  advances 
in  its  nut  in  one  revolution. 

PITCH,  To  —  To  plunge  in  a  fore-and-aft  direction. 

PITOT  TUBE  —  A  tube  with  an  end  open  square  to  the 
fluid  stream,  used  as  a  detector  of  an  impact  pres- 
sure. It  is  usually  associated  with  a  concentric  tube 
surrounding  it,  having  perforations  normal  to  the 
axis  for  indicating  static  pressure;  or  there  is  such 
a  tube  placed  near  it  and  parallel  to  it,  witli  a  closed 
conical  end  and  having  perforations  in  its  side.  The 
velocity  of  the  fluid  can  be  determined  from  the 
difference  between  the  impact  pressure  and  the  static 
pressure,  as  read  by  a  suitable  gauge.  This  instru- 
ment is  often  used  to  determine  the  velocity  of  an 
aircraft  through  the  air. 

PLANE  OF  SYMMETRY  —  A  vertical  plane  through  the 
longitudinal  axis  of  an  aeroplane.  It  divides  the 
aeroplane  into  two  symmetrical  portions. 

PONTOON  —  (See  FLOAT.) 

PROPELLER  OR  AIR  SCREW  —  A  body  so  shaped  that  its 
rotation  about  an  axis  produces  a  thrust  in  the  di- 
rection of  its  axis. 

Disc-Area   of  Propellet The   total   area   of  a   circle 

swept  by  the  propeller  tips. 
Pitch  Of  —  The  distance  a  propeller  will  advance  in 

one  revolution,  supposing  the  air  to  be  solid. 
Race  —  The  stream  of  air  driven  aft  by  the  propeller 
and  with  a  velocity  relative  to  the  aeroplane  greater 
than  that  of  the  surrounding  body  of  still  air.      (Fre- 
quently called  slip-stream.) 

Slip  Of  —  The  difference  between  the  distance  a  pro- 
peller actually  advances  and  the  distance  it  would 
advance  while  making  the  same  number  of  revolu- 
tions in  a  solid  medium.  Usually  expressed  as  a  per- 
centage of  the  total  distance. 

Torque  Of  —  The  turning  moment  of  the  propeller. 
The  effect  of  propeller  torque  is  an  equal  reaction 
tending  to  rotate  the  whole  aeroplane  in  the  oppo- 
site direction  to  that  of  the  propeller. 

PUSHER  — (See  AEROPLANE.) 

PYLON  —  A  post,  mast  or  pillar  serving  as  a  marker  of 
a  flying  course.  Also  used  infrequently  to  designate 
the  control  masts  such  as  the  aileron  mast,  rudder 
mast,  elevator  mast,  etc. 

RAKE  —  The  angular  deviation  of  the  outer  end  of  a  wing 
from  a  line  at  right  angles  to  the  entering  edge. 

RELATIVE  WIND  —  The  motion  of  the  air  with  reference 
to  a  moving  body.  Its  direction  and  velocity,  there- 
fore, are  found  by  adding  two  vectors,  one  being  the 
velocity  of  the  air  with  reference  to  the  earth,  the 
other  being  equal  and  opposite  to  the  velocity  of  the 
body  with  reference  to  the  earth. 

RETREAT —  (See  SWEEP  BACK.) 

RIB  —  A  member  used  to  give  strength  and  shape  to  an 

aerofoil  in  a  fore-and-aft  direction. 
Web  —  A  light  rib,  the  central  part  of  which  is  cut  out 

in  order  to  lighten  it. 

Compression  —  A  rib  heavier  than  the  web  type  and  so 

constructed  as  to  resist  the  compression  due  to  the 

wire  bracing  of  the  aeroplane. 

Secondary  Nose  —  Small  ribs  extending  from  the  front 

spar  to  the  nose  strip   (entering  edge).      Placed  be- 


No.MKNt  LATt  UK   1O|{  AERONAUTICS 


.•!•_•  i 


tween  tin-  iii.iin  rilis  to  give  Mi|i|inrt  to  the  fal.ru    n,  ..r 
tin-  entering  edge.     Sometimes  called   Stuli   Hibs. 

J(K,(.I.\(,  Tin-  art  (if  truing  up  .-in  aeroplane  ;ni<l  ki .  p 
ing  it  in  Hying  condition. 

Hii'  (  mil)  Tlic  rope  running  from  the  rip  pain  1  of  a 
balloon  to  tin-  basket,  tin-  pulling  of  which  causes 
immediate  deflation. 

HIP  1' \.\KI.  A  >trip  in  tin-  upper  part  of  a  balloon 
which  i*  torn  off"  when  immediate  deflation  is  desired. 

Hi  DIIKH        A   hinged  or  pivoted  Mirf-ice,  usually  more  or 
li -ss   flat   or  streamlined,  used   for  the   purpose  of  eon 
trolling  the  attitude  of  an  aircraft  about  its  vertical 
axi.s,  i.  e.,  for  controlling  its  lateral  movement. 

KriMiKii  BAH  —  A  bar  pivoted  at  the  center,  to  the  ends 
of  which  the  rudder  control  cables  are  attached.  The 
pilot  operates  the  rudder  by  moving  the  rudder  bar 

With    his     feet. 

lit  iiixii   POST       Tin-  post  to  which  the  rudder  is  hinged, 

generalh    forming  the   rear   vertical   member   of   the 

vertical   staliili/er. 
Sr  \  PLANE  —  An  aeroplane  fitted  with  pontoons  or  floats 

suitable  for  alighting  on  or  rising  from  the  water. 

(See  AEROPLANE.) 

SERPENT  —  A  short  heavy  guide  rope  used  with  balloons. 
SIHXINO —  A    binding   of   wire,    cord    or    other    material. 

I'siially  used  in  connection  with  joints  in  wood,  and 

cable  splices. 
SIHK  Si. i  PIMM.  —  Sliding  sideways  and  downward  toward 

the  center  of  a  turn,  due  to  an  excessive  amount  of 

bank.      It  is  the  opposite  of  skidding. 
SIM    U'ALK  —  A  reinforced  portion  of  the  wings  near  the 

fuselage  serving  as  a  support  in  climbing  about  the 

aeroplane.     Otherwise  known  as   running  board. 
SKIDDING —  Sliding  sideways  away  from  the  center  of  a 

turn,  due  to  an  insufficient  amount  of  bank.     It  is 

the  opposite  of  side  slipping. 

SKIDS — LANDING  GEAR  —  Long  wooden  or  metal  run- 
ners designed  to  prevent  nosing  of  a  land  machine 

when  landing,  or  to  prevent  dropping  into  holes  or 

ditches    in    rough    ground.     Generally    designed    to 

function  in  case  the  wheels  should  collapse  or  fail  to 

act. 
•]-ai[  —  A  skid  supporting  the  tail  of  a  fuselage  while 

on  the  ground. 
H'ing  —  A   light  skid  placed   under  the  lower  wing  to 

prevent  possible  damage  on  landing. 
SKIS  FRICTION  —  Friction  between  the  air  and  a  surface 

over  which  it  is  passing. 
SUP  STREAM  —  (See  PROPELLER  RACK.) 
SOMIIM;  MAI  IIINE —  (See  GLIDER.) 
BPAN-WING —  Span  is  the  dimension  of  a  surface  across 

the  air  stream. 
If  ing  Span   or  Spread  of  a  machine  is  length  overall 

from  tip  to  tip  of  wings. 
SPARS-WING — Long   pieces   of   wood   or   other   material 

forming  the  main  supporting  members  of  the   wing, 

and  to  which  the  ribs  are  attached. 
SPHKAD —  (See  SPAN.) 
STABILITY  —  The  quality  of  an  aircraft  in   flight  which 

causes  it  to  return  to  a  condition  of  equilibrium  after 

meeting  a  disturbance. 
Directional  —  That  property  of  an  aeroplane  by  virtue 


of  which  it  ten. Is  t..  hold  a  straight  course.  That  is. 
if  a  machine  ti  mis  constantly  to  xeer  ori  its  course 
"<••  ..I  the  controls  by  the  pilot 

to  keep  it  on  its  course,  it  is  said  to  lack  directional 
stability . 

Dynamical  —  The  quality  of  an  aircraft  in  flight  which 
causes  it  to  return  to  a  condition  of  equilibrium  after 
its  attitude  has  been  changed  In  mii.ui;>  ...m.  di> 
turbance,  e.  g.,  a  gust.  This  return  to  equilibrium 
is  due  to  two  factors;  first,  the  inherent  righting  mo- 
ments of  the  structure;  second,  the  damping  of  the 
oscillations  In  the  tail,  i  tc. 

Inherent  —  Stability  of  an  aircraft  due  to  the  disposi 
lion   and  arrangement   of   its   fixed   parts,   i.   e..  that 
property  which  causes  it  to  return  to  its  normal  atti- 
tude of  flight  without  the  use  of  the  controls. 
Lateral  —  The   property  of  an  aeroplane  by   virtue  of 
which  the  lateral  axis  tends  to  return  to  a  horizontal 
position  after  meeting  a  disturbance. 
Longitudinal  —  An    aeroplane    is    longitudinally    stable 
when  it   tends  to  fly  on  an  even  keel  without  pitch- 
ing or  plunging. 

Statical — In  wind  tunnel  experiments  it  is  found  that 
there  is  a  definite  angle  of  attack  such  that  for  a 
greater  angle  or  a  less  one  the  righting  moments  are 
in  such  a  sense  as  to  tend  to  make  the  attitude  re- 
turn to  this  angle.  This  holds  true  for  a  certain 
range  of  angles  on  each  side  of  this  definite  angle; 
and  the  machine  is  said  to  possess  "  statical  stabil- 
ity "  through  this  range. 

STABILIZER  —  Balancing  planes  of  an  aircraft  to  promote 

stability. 

Horizontal  —  A   horizontal    fixed   plane   in   the   empan- 

nage  designed  to  give  stability  about  the  lateral  axis. 

J'ertical  —  A  vertical  fixed  plane  in  the  empannage  to 

promote  stability  about  the  vertical  axis. 
Mechanical  —  Any    mechanical   device   designed    to   se- 
cure stability  in  flight. 

STABILIZING  FINS  —  Vertical  surfaces  mounted  longi- 
tudinally between  planes,  to  increase  the  keel  plane 
area. 

STAGGER  —  The  amount  of  advance  of  the  entering  edge 
of  a  superposed  aerofoil  of  an  aeroplane,  over  that  of 
a  lower,  expressed  as  a  percentage  of  the  gap.  It 
is  considered  positive  when  the  upper  aerofoil  is  for- 
ward. 

STALLING  —  A  term  describing  the  condition  of  an  aero- 
plane which,  from  any  cause,  has  lost  the  relative 
speed  necessary  for  steerageway  and  control. 

STATION  —  The  points  at  which  struts  join  the  longerons 
in  a  fuselage,  are  termed  stations  and  are  numbered 
according  to  some  arbitrary  system.  Some  makers 
begin  with  No.  1  at  the  nose  plate  aiiH  number  to- 
ward the  rear.  Other  makers  begin  with  0  at  the 
tail  post  and  number  toward  the  front. 

STATOSCOPE —  An  instrument  to  detect  the  existence  of  a 
small  rate  of  ascent  or  descent,  principally  used  in 
ballooning. 

STAY  —  A  wire,  rope,  or  the  like  used  as  a  tie  piece  to 
hold  parts  together,  or  to  contribute  stiffness;  for 
example,  the  stays  of  the  wing  and  body  trussing. 

STREAMLINE-FLOW  —  A  term  used  to  describe  the  cmidi 


322 


TEXTBOOK  OF  APPLIED  AERONAUTIC  ENGINEERING 


tion  of  continuous   flow   of  a   fluid,   as   distinguished 
from  eddying  flow,  where  discontinuity  takes  place. 

STREAMLINE-SHAPE  —  A  shape  intended  to  avoid  eddying 
or  discontinuity  and  to  preserve  streamline-flow,  thus 
keeping  resistance  to  progress  at  a  minimum. 

STRINGERS  —  A  term  applied  to  the  slender  wooden  mem- 
bers running  laterally  through  the  wing  ribs  for  the 
purpose  of  stiffening  them. 

STRUT  —  A  compression  member  of  a  truss  frame;  for  in- 
stance, the  vertical  members  of  the  wing  truss  of  a 
biplane. 

STRUT-INTERPLANE  —  A  strut  holding  two  aerofoils. 

SUPPORTING  SURFACE  —  Any  surface  of  an  aeroplane  on 
which  the  air  produces  a  lift  reaction. 

SUSPENSION  BAND  —  The  band  around  a  balloon  to  which 
are  attached  the  basket  and  the  main  bridle  suspen- 
sions. 

SUSPENSION  BAR  —  The  bar  used  for  the  concentration  of 
basket  suspension  ropes  in  captive  balloons. 

SWEEP-BACK  —  The  horizontal  angle  between  the  lateral 
(athwartship)  axis  of  an  aeroplane  and  the  entering 
edge  of  the  main  planes. 

TACHOMETER  —  An  instrument  for  indicating  the  number 
of  revolutions  per  minute  of  the  engine  or  propeller. 

TAIL  CUPS  —  The  steadying  device  attached  at  the  rear 
of  certain  types  of  elongated  captive  balloons. 

TAIL-NEUTRAL  —  A  tail,  the  horizontal  stabilizer  of  which 
is  so  set  that  it  gives  neither  an  upward  lift  nor  a 
downward  thrust  when  the  machine  is  in  normal 
flight. 

Positive  —  A  tail  in  which  the  horizontal  stabilizer  is  so 
set  as  to  give  an  upward  lift  and  thus  assist  in  carry- 
ing the  weight  of  the  aeroplane  when  it  is  in  normal 
flight. 

Negative  —  One  in  which  the  horizontal  stabilizer  is  so 
set  as  to  give  a  downward  thrust  on  the  tail  when  the 
machine  is  in  normal  flight. 

TAIL  POST  —  The  vertical  strut  at  the  rear  end  of  the 
fuselage. 

TAIL  SKID  —  A  skid  supporting  the  tail  of  a  fuselage  while 
on  the  ground. 

TAIL  SLIDE  —  A  steep  descent,  tail  downward.  Usually 
caused  by  stalling  on  an  attempt  to  climb  too  steeply. 

THIMBLE  —  An  elongated  metal  eye  spliced  in  the  end  of 
a  rope  or  cable. 

TRACTOR —  (See  AEROPLANE.) 

TRAILING  EDGE  —  The  rearmost  portion  of  an  aerofoil. 

TRIPLANE  —  A  form  of  aeroplane  whose  main  supporting 
surface  is  divided  into  three  parts,  superimposed. 

TRUSS  —  The  framing  by  which  the  wing  loads  are  trans- 
mitted to  the  body ;  comprises  struts,  stays  and  spars. 

UNDERCARRIAGE  —  (See  LANDING  GEAR.) 

VETTING  —  The  process  of  sighting  by  eye  along  edges 
of  spars,  planes,  etc.,  to  ascertain  their  alignment. 
An  experienced  man  can  detect  and  remedy  many 
faults  in  alignment  by  this  method. 

VOL-PIQUE' —  (See  NOSE  DIVE.) 
VOLPLANE  —  To  glide. 

WARP  —  To  change  the  form  of  the  wing  by  twisting  it, 
usually  by  changing  the  inclination  of  the  rear  spar 
relative  to  the  front  spar. 


WASHIN  —  A  progressive  increase  in  the  angle  of  inci- 
dence from  the  fuselage  toward  the  wing  tip. 

WASHOUT  —  A  progressive  decrease  in  the  angle  of  inci- 
dence from  the  fuselage  toward  the  wing  tip. 

WEIGHT-GROSS —  (See  LOAD,  FULL.) 

WINGS — The  main  supporting  surfaces  of  an  aeroplane. 
Also  called  Aerofoils. 

WING  FLAPS — (See  AILERON.) 

WING  LOADING —  (See  LOADING.) 

WING  MAST  —  The  mast  structure  projecting  above  the 
wing,  to  which  the  top  load  wires  are  attached. 

WING  RIB  —  A  fore-and-aft  member  of  the  wing  structure 
used  to  support  the  covering  and  to  give  the  wing 
section  its  form.  (See  RIB.) 

WING  SPAR  OR  WING  BEAM  —  A  transverse  member  of  the 
wing  structure.  (See  SPARS-WING.) 

WIRES  — 

Drift  —  Wires  that  take  the  drift  load  and  transfer  it 
through  various  members  to  the  body  of  the  aero- 
plane. 

Flying — The  wires  that  transfer  to  the  fuselage,  the 
forces  due  to  the  lift  on  the  wings  when  an  aeroplane 
is  in  flight.  They  prevent  the  wings  from  collapsing 
upwards  during  flight. 

Landing  —  The  wires  that  transfer  to  the  fuselage,  the 
forces  due  to  the  weight  of  the  wings  when  an  aero- 
plane is  landing  or  resting  on  the  ground. 
Staggei The    cross    brace    wires    between    the    inter- 
plane  struts  in  a  fore-and-aft  direction. 

YAW  —  To  yaw  is  to  swing  off  the  course  and  turn  about 
the  vertical  axis  owing  to  side  gusts  of  wind  or  lack 
of  directional  stability. 

Angle  Of — The  temporary  angular  deviation  of  the 
fore-and-aft  axis  from  the  course. 

ACCELERATION  —  The  rate  of  increase  of  velocity. 

CENTER  OP  GRAVITY  —  The  center  of  gravity  of  a  body 
is  that  point  about  which,  if  suspended,  all  the  parts 
will  be  in  equilibrium,  that  is,  there  will  be  no  tend- 
ency to  rotation. 

CENTRIFUGAL  FORCE  —  That  force  which  urges  a  body, 
moving  in  a  curved  path,  outward  from  the  center  of 
rotation. 

COMPONENT  —  A  force  which  when  combined  with  one  or 
more  like  forces  produces  the  effect  of  a  single  force. 
The  single  force  is  regarded  as  the  resultant  of  the 
component  forces. 

DENSITY  —  Mass  per  unit  of  volume;  for  instance,  pounds 
per  cubic  foot. 

EFFICIENCY —  (Of  a  machine.)  — The  ratio  of  output  to 
input  of  power,  usually  expressed  as  percentage. 

ELASTIC  LIMIT — The  greatest  stress  per  unit  area  which 
will  not  produce  a  permanent  deformation  of  the  ma- 
terial under  stress. 

ELONGATION  —  When  any  material  fails  by  tension  it 
usually  stretches  and  takes  a  permanent  set  before  it 
breaks.  The  ratio  of  this  permanent  elongation  to 
the  original  length,  expressed  as  a  percentage,  is  a 
measure  of  the  elongation. 

ENERGY  —  The  capacity  of  a  body  for  doing  work.  Hc.it 
is  a  form  of  energy.  Any  chemical  reaction  that  gen- 
erates heat  or  electricity  liberates  energy.  Bodies 


NOMENCLATURE    1O1{   .\KMo.\.\l    IKS 


in  i;.     piissi  ,s    i  111  rax     |i\    virtue   of    liixinu    work    done 
ii|inii   tin  in 

I  viiiiiiiiMM         \\lnn    tun    or    more    turns     u-t     upon    a 

hodx    in   such   .1   wax    that    im  iiuitiuii   results,   then    i> 
saiil  I"  IM-  equilibrium. 

II  xi  i"ii    "i     >\ihix          Tin     ral in   of    tin-    load    required    to 

:  nliiri-    in    n    slnu-tur.-il    member    to    tin-    usual 
uorkmg  load  tin-  member  is  designed  In  carrx.      Thus 
if  a   ini-iiilii-r   hr  designed   to  carry   a   loud   »t    ..mi   Ihs. 
nnd  it  would  require  a  load  of  -JIMIII  His.  to  cause  fail- 
ure, the  factor  of  .safety  would  lie  four. 
I  -"I    I'. MM)        The   foot  pound  is  n  unit  of  work.      It   is 
equal   to  a  force  of  one  pound  acting  through  a  dis 
taiicc  of  one  foot.      This  is  a  font  pound  nl  energy. 

ISHITM — That  property  of  a  body  by  virtue  of  which 
it  resists  any  attempt  to  -start  it  if  at  rest,  to  stop 
it  if  in  motion,  or  in  any  wax  to  cli.mge  either  the 
direction  or  xilocity  of  motion,  is  called  Inrrlia. 

M  x-s  The  mass  of  a  body  is  a  measure  of  the  quantity 
of  material  in  it. 

MMXHNI  Moment  is  the  product  of  n  force  times  its 
lexer  arm.  It  is  usually  expressed  in  Inch-I'oundi. 

\lo\u  NII  \i  Momentum  is  the  product  of  the  mass  and 
velocity  of  a  moving  body.  It  is  a  measure  of  the 
quantity  of  motion. 

POWER  —  Power  is  the  time  rate  of  doing  work. 

llnrir power  —  The  horsepower  is  a  unit  of  work.  One 
horsepower  represents  the  performance  of  work  at 
the  rate  of  33,000  foot-pound*  per  minute,  or  550 
foot  pounds  per  second. 

RESTLTANT  OF  A  FORTE  —  The  resultant  of  two  or  more 
forces  is  that  single  force  which  will  produce  the 
same  effect  upon  a  body  as  is  produced  In  the  joint 
action  of  the  component  forces. 

STRK*S  —  •  The  internal  condition  of  a  body  under  the  ac- 
tion of  opposing  forces.  The  unit  of  measure  is 
usually  pounds  per  square  inch. 

Comprrttion  —  When   forces  are  applied  to  a  body  in 
such  n  war  as  to  tend  to  crush  it,  there  results  a  com  - 
prcssive  stress  in  the  body. 
Trntion  —  When  forces  are  applied  to  a  body  in  such 


a   way  as  to  tend   to  separate  or  pull   it  apart,   the 

Iwidx    is   said  t.i  I tension  or  a  tensile  stress  has 

1«  i  n  produced  within  it. 

Shrur        When   external   forces   are   applied   in   such   a 
wax     is    ti>   cause    a   tendency    for   particles   of   a   body 
to  slip  or  slide  past   each  other,  there  results  a  sin   ir 
mg  stress  in  the  hodx. 
>  in  \ix —  Strain   is   the  deformation   produced   in  a  body 

by    the   application  of  external    f"! 

ToHvi'K  U  In  n  forces  are  so  disposed  as  to  cause  or 
tend  to  cause  rotation,  then-  is  produced  a  turning 

in nl    which    is   also   called    tori|iie.      It    is    usually 

measured  in  inch  pounds.  Thus  if  a  force  of  10 
pounds  be  applied  tangcntially  to  the  rim  of  a  wheel 
of  lO-inch  radius,  the  torque  or  turning  moment  will 
be  KM)  inch  pounds. 

L'LTIMATE  STRENGTH  —  The  load  per  square  inch  re- 
quircd  to  produce  fracture. 

VELOCITY  —  In  uniform  motion,  the  distance  passed  over 
in  n  unit  of  time,  as  one  second.  This  may  also  be 
obtaitied  hy  dividing  the  length  of  any  portion  of 
the  path  hy  the  time  taken  to  describe  that  portion, 
no  matter  how  small  or  great. 

In  variable  motion,  where  velocity  varies  from  (Miint 
to  point,  its  value  at  any  point  is  expressed  as  tin- 
quotient  of  an  infinitely  small  distance,  containing 
tin-  given  point  hy  the  infinitely  small  portion  of 
time  in  which  this  distance  is  described. 

WORK  —  The  product  of  a  force  by  the  distance  described 
in  the  direction  of  the  force  by  the  point  of  applica- 
tion. If  the  force  moves  forward  it  is  called  a  work- 
ing force,  and  is  said  to  do  the  work  expressed  hy 
this  product;  if  backward,  it  is  called  a  resistance, 
and  is  then  said  to  have  the  work  done  upon  it,  in 
overcoming  the  resistance  through  the  distance  men- 
tioned (it  might  also  be  said  to  have  done  negative 
work). 

In  a  uniform  translation,  the  working  forces  do  an 
amount  of  work  which  is  entirely  applied  to  overcom- 
ing the  resistance*. 


The  Metric  System 


The  Metric  System 

The  fundamental  unit  of  the  metric  system  is  the  METER  (the  unit 
of  length)  From  this  the  units  of  mass  (GRAM)  and  capacity 
(LITER)  are  derived.  All  other  units  are  the  decimal  subdivisions  or 
multiples  of  these.  These  three  units  are  simply  related,  so  that  tc 
all  practical  purposes  the  volume  of  one  kilogram  of  water  (one  liter) 
iv  ,  (jiial  to  mi'-  cubic  decimeter. 


One  short  ton  equals  ahout  .91  metric  ton;   one  long  ton  equals  abou 
1.02  metric  tons,  and  one  kg.  equals  about  2.20  pounds. 


EQUIVALENTS 
1  METER  =  39.37  INCHES 


PREFIXES                            MEANING                                        UNITS 

Legal  Equivalent  Adopted 

by  Act  of 

Congress,  July  28,  1866. 

MILLI-   =;  one  thousandth        Viooo              -001 
CENTI-   =  one  hundredth         Moo                .01            METER    for   length 

Length 

DEC1            one  tenth                 Via                 -1 
unit  :     me                                                   1-                GRAM    for    mass 

Centimeter 
Meter 

r 

0.3937 

3.28 

inch 

feet 

IllcTO-  =  on"    hundred            l«K          100.                LITER    for    capacity 

Meter 
Kilometer 

= 

1.094 
0.621 

yards 
statute  mile 

KILO-      —one  thousand                   i      1000. 

Kilometer 

= 

0.5396 

nautical   mile 

The    metric    terms    are    formed    by    combining    the    words    "METER, 

Inch 
Foot 

_ 

2.540 
0.305 

centinit  ters 
meter 

"GRAM,"  and   "LITER"   with  the  six  numerical  prefixes. 

Yard 

— 

0.914 

meter 

Length 

Statute  mile 

— 

1.61 

kilometers 

10  milli-meters     mm           =      1   centimeter                                     cm 

Nautical  mile 

= 

1.853 

kilometers 

10  centi-meters                      —      1   deci-meter                                        dm 

. 

10  deci-meters                      =      1  METER    (about    40    inches)      m 

Area 

10  meters                             =     1  deka-meter                                  dkm 

Sq.  centimeter 

— 

0.155 

sq.   inch 

10  deka-meters                      =      1   hectometer 

•    Sq.  meter 

— 

10.76 

sq.   fiet 

10  hecto-meters                            1  kilo-meter    (about  %  mile)        km 

Sq.  meter 

— 

1.196 

sq.   yards 

Mass 

Hectare 

=: 

2.47 

acres 

10  milligrams      mg            =1   centi-gram                                         eg 
10  centi-grams                       =      1   deci-gram                                          dg 
10  deci-grams                        —      1   GRAM   (ahout   15  grains)             g 
10  grains                              =     1  deka-gram                                    dkg 
10  deka  grams                       =      1   hecto  gram                                        hg 
10  hecto-grams                      =      1  kilogram    (about  2  pounds)        kg 

Sq.  kilometer 
Sq.   inch 
Sq.  foot 
Sq.  yard 
Acre 
Sq.  mile 

= 

0.386 
6.45 
0.0929 
0.836 
0.405 
2.59 

sq.  mile 

sq.    centimeters 
sq.  meter 
sq.  meters 
hectare 
sq.  kilometers 

Capacity 

Volume 

10  nulli-liters     ml               =1  ccnti-liter                                         cl 

Cu.  centimeter 

= 

0.0610 

cu.  inch 

10  centi-liters                         =      1   deci-liter                                             dl 

Cu.  meter 

— 

35.3 

cu.   feet 

10  deci-liters                        =      I  LITER  (ahout  1  quart) 

Cu.  meter 



1.308 

cu.   yards 

10  liters                                =     1  deka-liter                                       dkl 

Cu.  inch 



16.39 

cu.  centimeters 

10  deka-liters                         =      1   hecto-liter   (ahout  a  barrel)          hi 

Cu.   foot 

— 

0.0283 

cu.  meter 

10  hecto-liters                      =     1  kilo-liter                                           kl 

Cu.  yard 

= 

0.765 

cu.  meter 

The    square    and    cubic    units    are    the    squares    and    cubes    of    the 

Capacity 

linear  units. 

The  ordinary  unit  of  land  area  is  the  HECTARE    (ahout  2%    acres). 

Milliliter 

— 

0.0338 

U.   S.  liq.  ounce 

Length 

Milliliter 
Liter 

_ 

0.2705 
1.057 

apoth.   drain 
U.   S.  liq.   quarts 

1.000  millimeters    (mm)    or  100  centimeters    (cm)  =  1  meter    (m). 
1.000  m  =  1  kilometer   (km). 

Liter 
Liter 
Dekaliter 

z! 

0.2642 
0.908 
1.135 

U.   S.  liq.   gallon 
U.   S.   drv  quart 
U.   S.   pecks 

Capacity 

Hectoliter 

— 

2.838 

U.   S.  bushels 

1,000  milliliters   (mil)  or  cubic  centimeters  (cc)  —  1  liter  (1). 
1,000  1  =  1  kilometer   (kl)   or  cubic  meter   (cm  m). 

U.  S.  liq.  ounce 
U.   S.  apoth.   dram 
U.  S.  liq.   quart 

zT 

29.57 
3.70 
0.946 

milliliters 
milliliters 
liter 

Weight 

U.  S.  dry  quart 

= 

1.101 

liters 

U.  S.  liq.  gallon 

— 

3.785 

liters 

1,000  milligrams    (mg)  =  1  gram   (g). 

U.   S.   peck 

—  - 

0.881 

dekaliter 

1.000  g=  1  kilogram    (kg).      1.000  kg  =  1   metric  ton. 

U.  S.  bushel 

— 

0.3524 

hectoliter 

A   dollar   is   divided   into   100   cents   or    1,000   mills,    just   as   the  meter 

is    divided    into    100    centimeters    or    1,000    millimeters.     And    as,     for 

Weight 

example,    2    dollars   and   25   cents   is   written  $2.25,    so   2   meters   and   25 

rrntimeters    is    conveniently    written    2.25m.      Meters,    liters    and    grams 
are   treated    in    the   same   way   as   dollars.      For    practical   purposes,    from 

Gram 
Gram 

= 

15.43 

0.772 

grains 
U.   S.  apoth.  scruple 

units   of  length    are   formed   the  squares,    cubic   or   capacity   measures    (a 
cubic   measure   10   cm.    on   each   edge,   or    1,000   cc.,    makes    1  liter)    and 

Gram 
Gram 

ii 

0.2572 
0.0353 

U.  S.  apoth.  dram 
avoir,  ounce 

the  weights  (1  cc.  of  water  weighs  1  gram). 

Gram 
Kilogram 

= 

0.03215 
2.205 

troy  ounce 
avoir,  pounds 

Length 

Kilogram 

zr 

2.679 

troy  pounds 

For    all    practical    purposes    3    feet   and    3%    inches    equal    1    meter    or 
100    centimeters,    and    1    inch    equals    2.5    cm.     The    exact    legal    equiva- 
lent for  the  United  States  is  39.37  inches  to  1m. 

Metric  ton 
Metric  ton 
Grain 
U.  S.  apoth.  scruple 

= 

0.984 
1.102 
0.0648 
1.296 

gross  or  long  ton 
short  or  net  tons 
grams 
grams 

Capacity 

U.  S.  apoth.  dram 

— 

3.89 

grams 

One  liter  equals  1.0567104  liquid  quarts  or  ahout  .91  dry  quart. 

Avoir,  ounce 

— 

28.35 

grams 

One  fluid  ounce  equals  about  29.57  milliliters  or  cc. 

Troy  ounce 

— 

31.10 

Jrams 

Weight 

Avoir,  pound 

— 

0.4536 

ilogram 

Troy  pound 

— 

0.373 

kilogram 

In    avoirdupois    weight    one    ounce    equals    nearly    28.25    grams;    one 

Gross  or  long  ton 

— 

1.016 

metric  tons 

pound,  exactly  453.5924277  g.  nearly  454  g.  or  454  kg. 

Short  or   net  ton 

0.907 

metric  ton 

LENGTHS 


INCHES 

MILLI- 
METERS 

INCHES 

CENTI- 
METERS 

FEET 

METERS 

U.  S.  Yards 

METERS 

U..S.  Miles 

KILO- 
METERS 

0.03937 

1 

0.3037 

1 

1 

=    0.304801 

1 

- 

0.914402 

0.62137    = 

1 

0.07874 

2 

0.7874 

=      2 

2 

=    0.609601 

1  093611 

1 

1 

1.60935 

0.11811 

3 

1 

•J..")4001 

3 

-    0.914402 

2 

— 

1.828804 

1.24274    = 

2 

0.15748 

4 

1.1811 

=      3 

3.28083 

=    1 

2.187222 

— 

2 

1.86411    = 

3 

0.19685 

— 

6 

1.5748 

=      4 

4 

=    1  219202 

3 

2.743205 

2 

3.21869 

0.23622 

6 

1.9685 

=      5 

5 

=    1.524003 

3.280833 

3 

2.48548    = 

4 

0.27559 

7 

2 

=       5.08001 

6 

=    1.828804 

4 

3  657607 

3                 = 

4.82804 

0.31496 

8 

2.3622 

=      6 

6.56167 

=    2 

4.374444 

— 

4 

3.10685    = 

5 

0.35433 

9 

2.7559 

=      7 

7 

=    2.133604 

5 

— 

4.572009 

3.72822    = 

6 

1 

25,4001 

3 

—      7.62002 

8 

=    2.438405 

5.468056 

5 

4 

6.43739 

2 

50.8001 

9 

=:    2.743205 

6 

— 

5  486411 

4.34959    = 

7 

3 

76.2002 

3.5433 

=      9 

9.84250 

=    3 

6.561667 

-  - 

6 

4.97096    = 

8 

4 

101.6002 

4 

=    10.16002 

13.12333 

=    4 

7 

— 

6  400813 

5 

8.04674 

6 

127.0003 

5 

=    12.70003 

16.40417 

=    6 

7.655278 

_ 

7 

5.59233    = 

9 

6 

152.4003 

6 

==    15.24003 

19.68500 

=    6 

8 

— 

7  315215 

6 

9.65608 

7 

177.8004 

7 

—    17.78004 

22.96583 

8.748889 

. 

8 

7 

11.26541! 

8 

203.2004 

8 

—    20.32004 

26.24667 

—    g 

9 

_ 

8  229616 

8 

12.8747H 

9 

22S.6005                      9 

-    22.86005                 29  52750 

=    9                                 9.842500 

-- 

9 

9 

14.48412 

324 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


JAN  25  1934 


Jfctt  26 


NOV  24 


'  ^Y  USE 


14  1953 


LD21-100m-7,'33 


YE  018' 


7  o 


UNIVERSITY  OF  CALIFORNIA  UBRARY 


